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The mpg confusion

Filed under: — gavin @ 23 September 2008 - (Español) (Français)

What reduces emissions more?
A. Someone swapping their old SUV (which gets 12 miles per gallon) for a hybrid version (18 mpg) or
B. someone upgrading their 25 mpg compact to a new 46 mpg Prius?
(ignore for a minute manufacturing issues or driving habits and assume the miles driven are the same).

The surprising answer (for those who don’t work it out) is A. It’s easy enough to see why this is the case. If the driving distance is 100 miles, then for case A the saving in fuel used (and hence emissions) is 100/12-100/18 = 2.8 gallons, while for B, you have 100/25-100/46 = 1.8 gallons. The confusion arises because people like to think linearly about numbers, not inversely, and so tend to assume that a similar change in mpg has a similar impact on fuel usage. This is not however the case – improvements in efficiency at the low end of the scale are much more useful at reducing emissions. This is actually a very general point – when trying to raise efficiency it is always sensible to start with the least efficient processes.

This confusion got some attention a couple of months ago after a piece that was published in Science by Larrick and Soll. They tested peoples instinctive reactions to changes in mpg numbers and found that people very often got it wrong, leading to less than optimal decisions. They also tested a different way of giving fuel usage information (the number of gallons used per mile), and since this is linear in emissions, people made the correct judgment much more often (it’s worth noting that the standard in most of Europe is already litres per 100 km). Rewritten in those terms, the choices above become:

A. Someone swapping their old SUV (which takes 8.3 gallons to go 100 miles) for a hybrid version (5.6 gallons/100 miles) or
B. someone upgrading their 4 gallons/100 miles compact to a new 2.2 gallons/100 mile Prius?

Much easier, right? The authors of the Science piece are trying hard to get US manufacturers and the EPA to switch over from mpg to this new standard (though they prefer gallons/10,000 miles). It all seems eminently sensible to us.

356 Responses to “The mpg confusion”

  1. 301
    Phillip Shaw says:

    I own a 2004 Honda Insight and can testify that it is a wonderful commuter car. I get about 60 mpg in mild weather and about 55 mpg with the AC on. To compare the sales figures for the Insight and Prius really doesn’t make much sense. The Insight was the first hybrid on the american market and was intended to demonstrate that there was a market for hybrids. It was designed quickly and on a relatively small budget. Many components were borrowed from the Honda Civic and if you look under the hood you’ll see that some brackets and mountings are sawn off extrusions. Certainly not optimized for mass production. I’ve heard anecdotally that Honda lost money on every Insight sold, but it accomplished its goal. When I bought mine in 2004 there were waiting lists for Insight buyers at many Honda dealers, and the Insights have a strong resale value. I have even had strangers come up and offer to buy mine.

    The Prius, on the other hand, is a much more ‘finished’ design. Toyota made a number of smart decisions in its design and marketing so it is not surprising that the Prius sales have been great. It will be interesting to see what new designs automakers develop in the next few years.

    Captcha is right on point – cars bodies

  2. 302
    matt says:

    #286 dagobert: #286 Believe it or not. I honestly went there and looked for the xls
    (Failed to see the irony at first… found the t-shirts, though.)

    Yeah, Al Gore is flush with cash from riding green–to the tune of a $50M to $100M Forbes estimates. You’d think that if ANYONE was motivated to commission a study and get a really aggressive plan out there it would be him. Even T Boone Pickens has a plan of sorts. His cost is $1T for 20%, and he believes wind can provide up to 25% of US.

    It’s really a shame that the leading spokesperson for Green in the US has nothing but a battle-cry and t-shirts. Why does he not have a plan put together by like minded engineers in the industry that understand this stuff? Either 1) he doesn’t want to pay for this study in spite of caring deeply, 2) He’s tried, and he’s been told it is impossible, 3)he doesn’t know a study would help, or 4) he doesn’t care, he just wants to fan the flames and make more $.

    For those upset about the two seater car comment, my tongue was firmly in cheek. My point was this: Everyone’s needs are different, and all to often people have a tendency to project their needs onto others (“I’d never need that, why does HE need that?”). Everyone has a million reasons why they need a 4 seater car over a two seater, and yet they are so quick to judge why someone does NOT need an SUV.

  3. 303
    matt says:

    #299 Bart Verheggen: A small documentary on the Dutch TV this week showed an Opel P-1 experimental car (refurbished in 1973) that got a mileage of 373 mpg (0.6 liter/100 km). It’s supposedly not entirely roadworthy as is, but it does show what’s possible when engineers put themselves to the task. But then nothing is done with it…

    If you poke around a bit on the web, you’ll see this car couldn’t go up a hill or perform well in stop and go traffic and was missing a lot of stuff that makes a car a car. There’s likely not any magic here, other than throwing away a lot of stuff.

  4. 304
    Mark says:

    re 303. So? You won’t get near 400 mpg in stop/go traffic. And that’s using 30 year old tech.


    Your denial that we can change demand for power and replace fossil fuels in twenty years is wrong and you’ll pick any hole to deny anything that says otherwise.

  5. 305
    Hank Roberts says:

    > Matt thinks ….
    Got any evidence for this claim?

  6. 306
    Jim Bullis says:

    Why not have two efficient two seaters that are each inexpensive? That will get a family of four where they want to go — and back. A great many families have two cars now.

    Or maybe they would want to keep one of the “muscle cars or mommy wagons” that they have now. I use quotes because I want to attribute this phrase to Jack Martin, a frequent PBS commenter.

  7. 307

    Matt (303): I’ve read that too, and the guy in the documentary fully acknowledges that the car isn’t up to the par. Still, I find 370 mpg (160 km/l) a remarkable feat for a 2500 lbs (1150 kg) car. It’s not just marginally more efficient than current cars, but an order of magnitude! That same guy suggested that a road-worthy car with the same technology should be able to get 100 mpg, still far better than current cars, even including hybrids. Even though that figure is not more than an educated guess, there’s potential that’s not being utilized, that’s for sure.

  8. 308
    RichardC says:

    297 Tuukka, it’s even easier. The used vehicle can be excluded from the equation entirely. The “final” mix will be “everything on the road today” plus one vehicle. Since the hybrid SUV buyer is purchasing a new car with less than average MPG, that person is degrading the fleet’s economy and so he’d be a better environmentalist by just keeping his old SUV, while the hybrid car buyer is improving the fleet’s economy. However, one really has to add the final user, the guy who sends a vehicle to the crusher, to get a holistic picture.

    287 Matt, just buy some of the tow-behind bicycle kid-trailers for your Insight. Hook one up for each kid, and you’re good to go! Have the last kid wave a red flag (gotta be safe when carting the soccer team to practice!) (Or do it the third-world way – strap them to the roof and hanging out the trunk. Perhaps add running boards…)

    292 Guy, the reason 350 ppm is irrelevant is because it can’t be done immediately, and the science is evolving. How about a 390 target? Same acts needed this year to achieve (going negative requires stopping the acceleration first), and by next year more will be known. We can’t know if the methane outgassing that happens to be happening at 386 is going to continue or was caused by 386 (hmm… that’s it, Intel is to blame!) VS 350 VS something unrelated to CO2, so the Objective Scientist stays out of it, leaving hot-heads like me to bray. The RC folks probably are mostly silent on it because it is outside their scope and any answer would be used against them and their goals. I think you should honour their choices, especially since you have plenty of data from others.

    302 Matt, so TBone’s plan would only take ~18 months of readily available funds to get to 20% renewables? The deed would take longer, but obviously there is no financial issue. Concurrently drop electrical demand by 1/3, increase CAFE to 50 mpg, and suddenly the USA is a world leader again!

    Your SUV argument doesn’t hold water. Only 1.8% of households in the US have 4 or more children so over 98% of households can be served by a 5 seater, such as the Prius. Add a trailer, and the pickup truck argument goes away too. (Yes, I’ve driven a seriously loaded Prius and trailer over the Rockies.) So 2% of households would be well-served by a three-row station wagon and almost nobody needs an SUV. Remember, an SUV’s primary purpose is to get around CAFE and the clean air act. They are poorly-built passenger cars designed to get through a loophole. Ironically, without environmental laws, very few SUVs would exist. Yes, you see them on commercials going through canyons, but that’s gotta be less than 1% of the use of 0.1% of SUV sales. Driving the automobile market based on 0.001% need is fuelish, and Detroit never would have done it without environmentalists using laws to try and meddle with Detroit’s business. “All financial activity migrates towards loopholes.”

  9. 309
    RichardC says:

    276 dagobert said about different programming markets for the Prius, ” So lets settle on “almost” all of the difference is a testcycle artifact.”

    Could be (I’d guess 2/3rds testcycle, 1/3 programming), and easy to pseudo-test. I can get my North American Prius down to 4.3 litres/ 100km (55mpg) without hypermileage techniques. This excludes highway driving, requires constant attention, and is often impossible anyway. Anne, what can you get with your European one? Other folks?

  10. 310
    matt says:

    #307 Bart: I’ve read that too, and the guy in the documentary fully acknowledges that the car isn’t up to the par. Still, I find 370 mpg (160 km/l) a remarkable feat for a 2500 lbs (1150 kg) car. It’s not just marginally more efficient than current cars, but an order of magnitude! That same guy suggested that a road-worthy car with the same technology should be able to get 100 mpg, still far better than current cars, even including hybrids. Even though that figure is not more than an educated guess, there’s potential that’s not being utilized, that’s for sure.

    I’m even more pessimistic on this car after doing some math. You’ve been duped.

    A gallon of gas has 115,000 BTU. If you had a engine that perfectly converted gasoline to rotational energy, and if the car was traveling at 50 MPH for the test, then the 7.6 hours of drive time would permit you 5.6HP.

    Do you believe that bucket of bolts was made to move at 50 MPH for 7.6 hours using just 5.6 HP? Ignore the motor/engine for a moment and just focus on moving a 2000 pound weight at 50 MPH on level ground. It takes around 12 HP for a Prius to achieve that, if Prius went on a diet and lost 50% of its weight.

    So, either you are being lied to, or the car has some magic low-drag design with ultra-low rolling resistance tires.

    Now, if we do consider the motor, the figure to look at is called “brake specific fuel consumption”. It’s units are grams of fuel per (KW*H). This car has a sfc number of 37.8 g/(KW*H). That is a world record by about 5X. This car would win the XPrize. You should buy it immediately, clean it up, and then collect the $10M.

    Or of course, it could be hoax.

    There is no magic. And I re-iterate that if the current Prius gets 45 MPG EPA HWY, then the 2010 Prius will get 10%, maybe 20% better. There is no magic happening, there’s no dramatic improvement coming. It’s a good improvement, but it doesn’t change the game.

  11. 311
    matt says:

    #308 RichardC: Remember, an SUV’s primary purpose is to get around CAFE and the clean air act.

    No, the primary purpose of an SUV is to provide the additional passenger space, 4WD with additional clearance for when weather demands it, towing power, and cargo space. A low-slung 4WD will not help you in snow. A pickup doesn’t provide the passenger seating, a minivan doesn’t provide the clearance for snow. The SUV addresses a unique segment that the other segments cannot address. The heritage of the SUV is indeed a working vehicle–Jimmy, Jeep, Landcruiser. Those cars existed to solve a need that people had to do their job.

    All cars have added weight and luxury at a dissappointing rate. Heck, the weight of the Prius is going UP, and its as laden with useless things (heavier electric windows, energy robbing AC) because consumers demand those features.

    Have some SUVs just gone over the top as status symbols? Absolutely. Does everyone need them? Of course not. But just like the Prius driver that goes on holiday overseas, everyone will allocate their carbon differently. If you live in the west, your PER CAPITA carbon footprint is modestly influenced by the car you drive, especially if you fly someplace on holiday or for business a few times per year.

    If you feel your blood pressure go up when you see one person driving an SUV, you need to refocus your energy on things that matter. An SUV owner that stays local for holiday is a hell of lot better for this planet than the Prius owner that takes a trip or two overseas.

  12. 312
    Guy says:

    #298 Ike and #308 Richard – I value both of your helpful responses. The reason why I know I am beginning to infuriate some people with this question is that (especially for Richard, this) – despite and and all uncertainties, Hansen has weighed in, and is referred to frequently as the world’s most senior climate scientist. He publicly lobbies for 350ppm, based on science. If ALL prominent scienitsts used your logic, which seems reasonable, I wouldn’t be so agitated about this. But the most important one of all has nailed his colours to the mast, and this is very hard to ignore.

    I appreciate that in one sense it might be academic whether or not the target is 350ppm or a pre-industrial 280ppm when the Tyndal Centre are currently forecasting 650ppm even with emissions reductions. But Hansen acknowledges a further potential downgrading of the target to a lower figure, Ike – 350ppm is seen as not definitively “safe”, but the maximum reasonable figure as a first step. And by setting a target too high (the most important point of all) such as 450ppm (currently the figure of choice of even many progressives), it greatly increases the risk of the entire multi-trillion dollar exercise being pointless, as a greater volume of CO2 will have been used over time that the planet can deal with. In other words – however unpalatable it is, if the only solution that has a realistic chance of success is one so extreme that ALL fossil fuels, say, should be phased out by 2030 (pertinent to this particular discussion of course), then that is the only rational course of action.

    As I have said before, this is of critical importance to policymakers. As someone involved in a climate change initiative, you have to base targets on science. James Hansen has advised 350ppm and coal phase-out as best targets based on available science, and further response from prominent climate scientists would be extremely helpful. So I am happy to “honour their choices” if they do disagree with Hansen’s logic, Richard, but this is very difficult without a statement as to why they disagree. There has to be an intellectual case put forward that the target is meaningless – from my multiple re-readings, the RC Target CO2 article seems to cautiously agree with all of Hansen’s logic, while stopping short of embracing his conclusions, which I simply don’t yet get (nor, I suspect, will policy makers).

  13. 313
    Nigel Williams says:

    5.2 l/100km for a 1500km trip along New Zealand in a Fiat 1.3l diesel tiptronic (excluding the fuel used by the inter-island ferry), and similar economy from a Citroen C4 diesel ditto.

    While these are good figures (releasing only around 120g of carbon per km) a good reason to own one of these is to go further when fuel rationing comes in. Folk can tie their Cryslers behind a cart horse, I would rather drive for as long as I can while leaving as much oil in the ground as possible! Thats while business as usual continues. When the wheels fall off and we hit the bolean condition of fuel today-none tomorrow it will all turn to custard with a rush. Lovelock is right, I guess – we may as well enjoy it while we can. The condemned man is entitled to a hearty meal!

  14. 314
    Larry Coleman says:

    310 matt Says:

    “A gallon of gas has 115,000 BTU. If you had a engine that perfectly converted gasoline to rotational energy, and if the car was traveling at 50 MPH for the test, then the 7.6 hours of drive time would permit you 5.6HP.”

    What assumptions did you use in this calculation? There’s not enough info in the quoted paragraph.

  15. 315
    Hank Roberts says:

    > Remember, an SUV’s primary purpose is to get around CAFE
    > and the clean air act.

    True. Look it up. Google could become a good friend.

    Look at the label on the inside of the driver’s door.
    It’ll warn you off.

    If you didn’t know the history — well put together in the Gladwell piece linked here — you’re proving the points he makes therein.

  16. 316
    matt says:

    Larry: What assumptions did you use in this calculation? There’s not enough info in the quoted paragraph.

    Of course there is. BTU (given by stating gallon of gas) to KWH is easy. Distance traveled from 1 gallon was given. Rate of travel (assumed at 50 MPH). Time of traveled (calculated). KWH/TIME gives you KW available for cruise at indicated rate. KW to HP is straightforward.

  17. 317
    RichardC says:

    305 Hank said, “> Matt thinks ….
    Got any evidence for this claim?”

    LOL, let’s check….

    310 Matt, 60 mpg is a reasonable estimate for the 2010 European Prius. A small car might get 80 mpg. If you think that isn’t game-changing, then you should study economics and oil. With 70 mpg CAFE, the oil companies would scream, “Uncle”, gas would cost $0.50 plus ($9?) tax, the US would be self-sufficient in oil, and Americans once again wouldn’t be able to find Iraq on a map. This MPG thing is core to changing ever so many games.

    311 Matt, the need-driven market for SUVs is tiny. Before CAFE, only a few SUVesque vehicles were made. They were offered, but very few folks wanted them. SO FEW THAT JEEP DIED, THEN AMC DIED AFTER BUYING JEEP, TOO! The US has further urbanized, more people live on paved and ploughed roads and family size has dropped. Thus, the tiny natural SUV market has certainly dropped even further. There was no problem until CAFE made SUVs popular. Then television commercials ramped up and push-selling made them popular. Like today – buy an SUV, get a huge discount and a rebate! What percentage of Detroit’s equity has been converted into SUVs? Detroit’s miserable failure to build decent cars that get good mileage helped push SUV sales too. The consumer’s options were: buy an SUV with a huge engine, buy a car that breaks and just plain sucks, or be a traitor and buy Japanese. So SUVs started showing up in parking lots and streets, and moms everywhere needed one just to see while backing up. Since SUVs have no bumper-height restrictions, regular cars get to have their occupants endangered. Now you have to buy an SUV or risk a bumper in the face! (talk about loony, all bumpers for all vehicles should be at a single height.) As to your contention that SUVs have ANY status symbol power, that’s ludicrous. SUVs are anti-status symbols. Perhaps at gas stations we should offer condolences to the unfortunates who drive them, “I’m so sorry you got stuck with such a horrid vehicle. It must hurt terribly having to be seen in it.” The Prius is the biggest status symbol on the road today. People have stood in the RAIN drooling over my car! Please, Matt, name ANY car that has more status than a Prius. And your mixing of CO2 activities is silly at best. Is it your contention that Prius owners are more likely to spew carbon in other activities than SUV owners?? The opposite is true, and you’re floundering badly. Wedges of carbon reduction are not invalidated by other wedges of carbon reduction.

    312 Guy, much of the stuff I’ve said here is similar. It would be child’s play to get off carbon, recession, and war and onto peace and prosperity. The problem is that folks are folks and they just won’t have it as it isn’t “the way things are/were done.” There are a few who are talented and brave enough to contemplate leaping to another paradigm, but most folks won’t. As you said, “seems to cautiously agree.” Well, that’s how science is done! It focuses on the unknown while distrusting the known. 99% means, “Let’s go play with that 1%.” To do otherwise would politicize it, and that’s galling to a scientist. Hansen addressed that by saying the only reason he’s doing it is personal. His grandchildren would someday ask why he didn’t, and he’d have no answer. Perhaps if other scientists started looking at their grandchildren a bit harder, they’d also do what they could never do.

    313 Nigel, Lovelock also said, “We desperately need a Moses to take us to the Arctic and preserve civilization.” This whole thing isn’t so hard to fix, but Moses would be laughed at by financiers, just as he was in Egypt. The real moral of the story (fable? Truth?) is that it’s only when death stalks the wealthy and connected does change occur. Trying to change diddly before then is tilting at windmills. Hybrid nukes, 70 mpg cars, and converting the military budget to renewables would save the planet. Odds of it happening? Zero. So we’re left with Moses. How many innocent people died via Moses’ hand? In a way, he and Noah were the ultimate mass-murderers. Was the result worth it?

    AND CAPTCHA SUCKS… 12th attempt: their points 13th: unknown Gordon 14th: follow- awards 15th: 0–7 Lumsden 16th: Restless confine 17th: Gordon of 18th rattler 7,440 18th 129 chantants 19th question late 20th loss afforded 21st Gillette 96.14 22nd Thorpe un- 23rd protecting J., 24th Tyson sur- 25th brother- staggered 26th Fletcher Sistine 27th of Francois 28th LAPHAM. out

  18. 318
    Ike Solem says:

    Instead of ppm, think in terms of gigatons of fossil fuel emissions. This is from Wallace Broeker, CO2 arithmetic, science magazine, limited access, unfortunately:

    “If we are ever to succeed in capping the buildup of the atmosphere’s CO2 content, we must make a first-order change in the way we view the problem. Most policies that have been discussed, including cap-and-trade systems and the Kyoto treaty, have treated the problem exclusively in terms of incremental reductions in CO2 emissions. These, however, will not stabilize atmospheric CO2 levels; they only slow the rate of increase. Instead, to actu- ally stop the increase, we must develop the concept of what might be called a “carbon pie.” Currently, for each 4 gigatons (Gt) of fossil carbon burned, the atmosphere’s CO 2 content rises about 1 ppm; including deforestation, we now emit about 8 Gt of carbon per year. Further, this four-to-one ratio will only change slowly in the coming decades. Hence, if we set a desirable upper limit on the extent to which we allow the CO2 content of the atmosphere to increase, then this fixes the size of the carbon pie. If, for example, this limit were to be double the pre-industrial CO2 amount (i.e., 560 ppm), then the size of the pie would be 720 Gt of carbon [i.e., 4 ×(560 – 380)]. Were the limit to be set at 450 ppm, the size of the pie would be only 280 Gt. required reduction schedule: An additional element would be necessary. The gap (see figure, right) between actual and allowed emissions would have to be made up either by purchase of CO2 allocated to poorer nations or by burial of CO2 captured from the atmosphere. Stemming the rise in CO2 would require participation of rapidly industrializing nations such as China and India. Under the pie concept, there would be an incentive for them to join for they would have a considerably longer period of time to adjust their CO2 emissions than rich nations. The sooner such an agreement was put into force, the better the situation would be for these nations. Until this is done, the size of the carbon pie will continue to shrink at a rate of 70 to 80 Gt per decade.”

    Notice that this introduces a new and oft-neglected uncertainty: the amount of fossil fuel emissions that stay in the atmosphere after emission. Historically, this has been about 50% – the rest goes into the ocean, soil or biomass pools, not into the atmosphere.

    If we fill up those pools, they will not be able to absorb more carbon – and there is evidence that this is actually happening at some level. If that happened, a 50% reduction in fossil fuel use would have no effect on the rate of atmospheric CO2 accumulation.

    That’s why solar/wind electric or biofueled cars are the only real long-term options (nuclear-sourced electricity being at best a short-term solution). However, there are some 200 gigatons of recoverable oil and gas alone remaining, as well as many more thousands of gigatons of coal and tar/shale oil.

  19. 319
    David B. Benson says:

    Ike Solem (318) — The estimate I’ve seen for 2007 CE is 8.5 GtC from fossil fuel and 1.6 Gtc from deforestation.

  20. 320
    Larry Coleman says:

    316 Matt:
    But you did not state the mpg in the paragraph I quoted so it was not obvious which value you used. That was the point of asking for clarification…so please not so huffy.

  21. 321
    matt says:

    320: Larry: But you did not state the mpg in the paragraph I quoted so it was not obvious which value you used. That was the point of asking for clarification…so please not so huffy.

    I didn’t mean to be huffy. There were no real assumptions made. You could have picked 100 MPH or 20 MPH as the speed and the math would have worked the same. So you could have run backwards, solved for the MPG, and then checked that in the article. Because that’s a one minute check, I assumed you weren’t asking about that and wanted more info overall on the process. Sorry for the misunderstanding.

  22. 322
    matt says:

    Google has published their energy plan and it’s a good read. They target 95% reduction in CO2 by 2030. They are about 50% alt energy in 2030, they believe we can hold the line on consumption increases, in fact reduce it a bit over today’s consumption (about 5%–meaning we consume a little less in 2030 that today), nat gas is the only fossil fuel still in use in 2030. Nuclear rises 10-20% between now and 2030. The also see an increase in new car MPG from 21.6 today to 45 MPG in 2030. Again, difficult, but achievable, and more important–possible.

    Overall, well thought out and well reasoned. It’s a shame Al Gore’s “10 years or else” group isn’t as realistic.

    Spend some time digesting this, as there’s a lot of good material inside. Personally, I’d bank more on nuclear in case one of the 5 alt energies ran into scale problems at some point. But there’s is a valid approach, and preferred if you don’t like nuclear.

  23. 323
    Rod B says:

    OT, but to keep it clean, Matt is essentially correct about the market-driven rationale for building the SUV (with 4WD being low on the priority). They built it on the truck chassis because that was easier than reinventing a near-redundant chassis, and, of course, they were solidly and acutely aware that truck chassis’ were outside of CAFE. To build the SUV simply to build something to beat CAFE would have made zero sense since they already had (and still have, at least through 2006) the best selling model of any truck (and of any vehicle for that matter) in the US.

  24. 324
    Rod B says:

    ps ….RichardC’s emotional rant not withstanding… ;-)

  25. 325
    dagobert says:

    #317 RichardC

    This will give you a rather good idea about consumption in Germany. Its a site where people trace their consumption long-term and has become kind of a standard for considering ‘mileage’ prior to purchasing a new car – more reliable than any of the standardized cycles. On average, the 500+ Priuses in the list consume around 5.23 l/100km but you’ll see that most of that includes autobahn, so your 4.9 l fit very well. Personally I’ve driven Priuses for around 20.000km and averaged slightly under 5 l/100km with a min of 3.8 l and a max of 8.1 l (autobahn averaging around 100 miles/h).

    Here’re two other examples with a VW Lupo 3l and Audi A2 3l.

    And some from the other side of he spectrum:

  26. 326
    dagobert says:

    #322 Matt
    Thanks for the link. Especially some of the studies quoted seem to be relatively complete.

    Is an interesting piece of work.

  27. 327
    Hank Roberts says:

    > subsidies, billions

    Definitely billions; how many billions depends on what numbers you include in your total:

    —-excerpt follows, hat tip to DeSmogBlog——-

    “… annual U.S. subsidy at an average of 39 billion dollars a year, when the costs of guarding oil lanes in the Persian/Arab Gulf, and the Alaska Pipeline are included. This does not include any costs from the Iraq war.

    Official U.S. government statistics from the Energy Information Administration (EIA) … stating that the oil and gas industry only received 2.15 billion dollars in 2007.

    … the U.S. subsidises oil production, … the cost of finding and producing oil for oil companies.

    Estimating U.S. oil and gas subsidies is very challenging. Subsidies rarely involve cash payments. Instead scores of U.S. government agencies and departments create hundreds of programmes to support the U.S. energy sector. And there is no requirement for the federal government to keep track of all this.

    Among the most common subsidies are construction bonds and research-and-development programmes at low interest rates or tax-free, assuming the legal risks of exploration and development in a company’s stead and income tax breaks.

  28. 328
    Guy says:

    Thanks RichardC #317. Are you suggesting that any CO2 target whatseover is seen as “political”? In which case – why discuss it (as in RC’s Target CO2?) or release a peer-reviewed paper on it? I can understand that Hansen’s lobbying is political (and I’ve noted he always prefaces his correspondance with a note that he is writing in a personal capacity). However, I’d have thought that the target itself – with all appropriate caveats – is not politcal, but simply scientific. Surely it has no ethical component – it simply says that such and such level of emission has a high probability of such and such outcome. The response – whether or not to embrace a target and act on it – is the political and ethical question, not a scientific one.

    Ike #318 – very interesting. But if I understand correctly, this is helpful at the stage of bartering which country does what, and how. The ppm target still needs to be set first, guided by science, then the gigaton wedges come into play?

    BTW – UK readers in particular might like this free downloadable book – – which simply looks at the numbers related to energy use, to see if anything adds up. It strives to have no agenda other than the numbers. While I found some of the assumptions and scenarios a little frustrating (why not look at the proposed pan-European response?), it makes an invaluable contribution imho, and is an excellent resource. Very pertinent to this thread in particular.

  29. 329

    matt #310 — is there another Barton or a Bartholomew on this thread? Because I know I didn’t write what you quoted.

  30. 330
    matt says:

    #329 BPL: is there another Barton or a Bartholomew on this thread? Because I know I didn’t write what you quoted.

    Yes, I noted it was “#307 Bart” which points to Bart Verheggen’s post.

  31. 331
    matt says:

    #326 Dagobert: Is an interesting piece of work.

    Indeed it is. A new paper from DOE is always a good thing to print and sit with a pen and calculator for a while.

    Some of this info was first published in a 2006 paper titled “High Wind Penetration Impact on US Wind Manufacturing Capacity and Critical Resources” which is another great read. It really help folks grasp just how much raw material is needed to do this. It’s staggering.

  32. 332
    dagobert says:

    #328 Guy
    “BTW – UK readers in particular might like this free downloadable book – – which simply looks at the numbers related to energy use, to see if anything adds up. It strives to have no agenda other than the numbers. While I found some of the assumptions and scenarios a little frustrating (why not look at the proposed pan-European response?)…”
    Yes, an awesome study on the whole. The author gives fair warning right from the start that, despite being one if not THE major factor, economics didn’t bother him too much and that shows a lot. Apart from that – a very good resource and definately a ‘must read’. Thanks for the link.

  33. 333
    CL says:

    Any comments on this Chinese electric car, said to become available at the end of this year ?

  34. 334
    Hank Roberts says:

    CL, their vaporware is real good. It appears to describe a gas-electric plugin hybrid, though it’s hard to be sure.

    They make computer batteries and gasoline engines, apparently.

    The few facts given — “2000 cycles” and “Fe” and twice the energy density of NiMH — suggests to me that they’re using some kind of nickel–iron (Ni–Fe) battery. That’s, um, futuristic right now as far as I know. One can hope.

    The claim their “Fe|” battery is more energy dense than NiMH would rule out LiFePO4 chemistry, which doesn’t risk explosions like current lithium ion battery chemistry if overcharged slightly.
    I think the Prius plugin is going to use LiFePO4 and availability of these delayed that model.

    Here’s a California refitter offering LiFePO4:

  35. 335
    sarah mcintee says:

    Could the experts please comment on the emissions impact of two-cycle engines in the US. How dirty are they? Is there an alternative small engine for landscape equipment that isn’t as dirty?

  36. 336
    RichardC says:

    334 Hank, interesting. Thanks. Assuming the batteries are similar in cost/kg as a deep cycle battery, that’s $300 per year of extra cost, not including labour, and every mile over 12 is at a serious disadvantage in efficiency and performance. Adding 360 pounds to a Prius is gonna hurt. I’m skeptical about using current batteries for primary power in a vehicle. Combustibles still can’t be beat for energy density, and weight is a prime factor in vehicle design.

    328 Guy, yes, any target would be political for two huge reasons:

    1. The scientific uncertainties are greater than two decades worth of CO2 emissions.

    2. The actual CO2 level can’t be calculated by adding mankind’s emissions to current atmospheric levels. Let’s pick a number at random, say 350 ppm, as a target, and try to figure out how to get there. Well, assume 600ppm of CO2 increase is in the pipeline, so mankind has to remove 636 ppm of CO2 to get to 350 ppm, unless mankind removes the CO2 in x months, then only 300 ppm of CO2 increase is in the pipeline. How do you name a target when humans aren’t the only player in the game? The wedges of pie game excludes all other players besides humans. Sorry, it doesn’t work that way. Humans came early to the game, but we’re still small.

    Gavin’s response was spot on. (It’s easy to agree with those who agree with me!) As low as we can get it as fast as we can do it. It’s like being in a car and noticing a brick wall ahead. You note, “I’m screwed,” brake as hard as you can, and hope the airbag will save enough of you so the doctors can patch you up. Does it matter what the calculations are for speed and survivability? We need to drop emissions, and let the paramedics figure out the next step. Matt’s 45 MPG by 2030 is a laughable way to continue to accelerate into the brick wall. He’s looking at absolute facts – it is absolute fact that CAFE could be raised to 60 MPG in 5 years, and yet he considers it impossible. Why? He doesn’t even see the brick wall, so “possible” is defined as BAU. With oil becoming scarcer, 45 mpg is probably far worse than BAU. He advocates doing less than nothing because “there is no brick wall.”

    Europe’s heat wave of 2003 was a bit of a wake up – the rich and powerful (the West) got a vision of death that didn’t just involve lesser humans. Katrina can be overlooked – can’t really pin that one, and the folks who died were largely Others, so it can be ignored. Folks in a position to decide will ignore that brick wall, or assume it will only kill Others, until we get significantly closer. There will be no action at all until it is patently obvious that the Arctic Ocean will become ice-free.

    The only scientifically solid answer so far is 280 ppm. Put it back where we found it. Remember that at 300 in the Eemian, the Arctic Ocean was ice-free. Other things were different – summer insolation, solar output, land use, soot, etc. It is quite obvious that the answer is somewhere below 350 ppm, which is why Hansen gave that number as a maximum. There is no scientific data on a 400+ ppm CO2 and 1700+ ppb CH4 sooty world with current solar output and continental configuration. This is all new ground, and so systems scientists are likely the best at guestimating, and systems scientists pretty much agree – at 386 and rising, the wreck is inevitable and a lot of blood is going to spill. Lovelock says 80 to 100% of humanity will die, no matter what we do now. That’s systems, which includes human nature, various jurisdictions, and profit motive. Climate modellers have no clue, can’t until after the fact, and exclude human nature by definition. They know it and have no qualms acknowledging it. They’re doing their best to quantify, but shoving the entire world into a program that fits in a computer… well, how do you quantify ice dynamics until you see ice dynamically decay? How do you quantify CH4 emissions until you see CH4 emit? How do you quantify ocean acidification and its results until you watch the ocean die? You’re asking the impossible.

    Why do you have a problem with 350? It’s solid policy and well-known. Are you just asking for more folks to publicly speak out? I think that’s a different question, and I’ll ask it:

    Of all the good (and patient) folks at RC, how many agree that Hansen’s 350 ppm initial target is a prudent path to take? Is it one which you feel will more likely will be revised upwards or downwards as the science becomes more solid? If you were to pick a number (it’s an office pool – if you’re right within 10 ppm, as determined by a climate model 20 years hence, you win a trillion dollars), what number would you pick as safe for initial (as in before carbon feedbacks) CO2 and CH4 concentrations, with safe defined as no more than a 1 metre rise in sea level by 2500? Assume we get to initial concentration instantly, and human CO2 and CH4 emissions become negligible for the duration.

    Can you see the problem? Say they come out averaging “290 ppm CO2 and 1000 ppb CH4.” Somebody is going to grab those numbers and put them in headlines. Perhaps the survey should stop with the first two questions — Is Hansen’s initial target a prudent policy to embark on, and is that target likely to be raised or lowered as the science solidifies? I suppose we’ll find out the answer to Gavin’s claim that nobody has called him shy…

  37. 337
    Guy says:

    #336 – Richard, thanks as ever. I agree with much of what you say, although I’m still not sure that a target is necessarily political. Surely the calculations as to what is (theroetically) possible in terms of emissions reductions are science? Note – I take this to mean not what is economically reasonable, but something that doesn’t violate all laws of nature, such as stopping all emissions literally overnight. And surely this is how it can be discussed in a peer-reviewed paper?

    Politics or not, as to your request for more RC opinion on the 350 target – absolutely! On these boards (and probably within the scientific community), the view that 280 is the ultimate figure to go for is widespread. But I can’t emphasise enough how far-out the 350 figure is compared to most public policy, which often regards 450 as pie-in-the-sky. If it is acknowledged that 450 is probably useless as a target, the climate science community must make urgent and strenuous efforts to make this clear. The support by NGOs and other organisations at still looks way too thin. At the moment, 350 is an unlikely goal for the simple reason that it is not supported enough.

    If 350 is correct, then the policy reccommendations of the IPCC (the climate gospel upon which policy is formed) do not go far enough. Ahead of Copenhagen 2009, this point will need to be repeatedly and forcefully made – otherwise we’ll waste trillions of dollars on something that more than likely won’t work. Where is the sense in that?!

  38. 338
    David B. Benson says:

    RichardC (336) — At the peak of the Eemian the CO2 concentration was 287 ppm according to the Petet et al. analysis of the Vostok ice core. I am fairly sure that the Arctic Ocean was not ice free then, but do not have a reference. What did happen was the melt of a considerable portion of the Greenalnd ics sheet; there is a graphic of it in IPCC AR4.

  39. 339
    RichardC says:

    337 Guy, political isn’t always a bad word. Perhaps the first target should be the absolute peak, and 400 ppm is almost certainly the lowest we can limbo. Under BAU, that’s about 5 years from now, assuming no degradation of sinks or other natural carbon feedbacks. 400 is high enough so that we can honestly say, “and we’ll have to get lower than that later.” No maybes, no impossible targets, just solid science most will agree is true. Thanks for the discussion. I’ve altered my stance. Hopefully it’s improved. Capcha says the Keeling curve is a: Responsibility meter

    338 David, the NSIDC says the Eemian was likely ice-free in summer.

  40. 340
    matt says:

    #336 RichardC: Europe’s heat wave of 2003 was a bit of a wake up – the rich and powerful (the West) got a vision of death that didn’t just involve lesser humans. Katrina can be overlooked – can’t really pin that one, and the folks who died were largely Others, so it can be ignored.

    The 35,000 dead from the heatwave was absolutely tragic.

    When you say “largely Others” do you mean “those that relied on public transportation?” Because those that had cars overwhelmingly left. Those that didn’t had no choice but to ride things out. In NOLA, 27% of people do not own a car. 120,000 people had no way out and were just left behind.

  41. 341
    dagobert says:

    matt, RichardC

    The ‘tragic’ European heat wave in 2003 was only tragic in statistics. 2003 was, in the memories of most Europeans, just a hot summer. The kids loved it. It was almost like 2006 only without the soccer. Nothing like streets littered with dead people or something. The political debate following was mostly centered around airconditioning in hospitals, the constrained personnel situation in many of the so called residents for the elderly which are nothing like sun city in Europe, keeping a certain minimum of medical presence especially in france, where traditionally almost the whole country goes on holiday in august and migrates to the coast if they can afford to do so (most doctors can) and a public debate about social indifference and not keepeng an eye out on your 90+ year old neighbors anymore. Things like that. I doubt very much that 2003 really was largely perceived as a prelude to global warming over here.

  42. 342
    Guy says:

    #339 – Cheers Richard, it is a very useful discussion, and I too need to get these issues totally clear in my mind, and revise opinions accordingly. Looked at like this, I guess the 350 target is appropriate in a way that 450 isn’t, even if the specific figure isn’t so important because it is an interim informed best guess. Though what I just wrote certainly isn’t widely understood at all, and I think there needs to be much greater clarity on this from climate scientists – right now. At least it is an appropriate target – and therefore surely worth publicly embracing.

    Very pertinent to all this, and this thread, is that today the UK government’s committee on climate change has revised upwards its reccommendations, moving from 60% emissions cuts by 2050 excluding aviation and shipping to a new target of 80% including those things ( On the radio this morning, the head of the committee Lord Turner was still not committing to specifics like airport expansion, and was talking about electric cars and “2nd generation biofuel” cars, which sounds very ill-considered. He was talking about eliminating fossil-fuel electricity generation by 2050.

    While the target is still below what is required as I understand it from Hansen, clearly it is getting closer. I think, in a way, it is actually strangely liberating to wholly embrace a more restrictive target – so for example, just accept that electic cars (or Hydrogen ha ha) are the only ones allowed on the road in 20 years, and work towards it (and of course colossal clean electricity expansion). Biofuels or even just efficiency improvements can be a distraction or worse – it is better to get where you ulitmately need to be much faster than limp on for longer doing more damage on the way.

    It may be a trivial analogy, but analogue TV is being switched off in 2012 here. When it was announced a few years ago, it was apocalyptic “our screens will go dark” stuff, but it’s just not a problem any more. We’ve adapted, and the world still turns – even the luddites get bored in the end! Of course this is more difficult by a factor of a few thousand, but I think the principle remains. Some people have an emotional attachment to things like petrol cars, but they will get over it…

  43. 343
    Jay Nickson says:

    Someone does care….

    On campus at UND, Grand Forks, ND, usa, during the summers there is a ca. 1984 VW Diesel Rabbit used daily.

    Judging from externals it may easily have 200,000 miles. Could be a great deal more, or less. I did not break in to read the odometer. & maybe they have already converted to using vegetable oil.

    Which suggests another question although the intuitive answer to “MPG Confusion” may be entirely correct in this case.

    What reduces emissions more?

    A. Someone swapping their old SUV (which gets 12 miles per gallon) for a hybrid version (18 mpg) or

    B. someone upgrading their 25 mpg compact to a new 46 mpg Prius?

    C. someone converting their 53 mpg 1984 VeeWee Drabbit (deisel rabbit) to use veggie oil?

    (For extra credit include energy and pollution estimates for raw material extraction, production, transportations and final disposal of vehicle)

  44. 344

    Matt, in a few years we may see whether reaching 100 MPG is possible or not: Loremo (low resistance mobile) is planning to have their petrol car on the market in 2010, and it’s supposed to drive at around 2 l/100 km (>120 MPG). See eg,en/

  45. 345
    dagobert says:

    Bart Verheggen #344
    They’ve now been working on it for 13 (thirteen) years and all they have for a concept is a light car with good aerodynamics. There is absolutely nothing new about that, except maybe (for some) the realisation that bringing a car to market is very, very difficult and that fancy, weight saving design is worth nothing when you open the door and your seats get wet.

  46. 346
    Hank Roberts says:

    CSIRO has an interesting device well into testing:

  47. 347
    topher mira says:

    I convert diesels to run on waste vegetable oil, and like to ride bikes. Closed carbon cycle emissions seem to be more sustainable than fossil fuel emissions.

    Too bad we are so addicted to our lifestyle of driving. I actually live in my veg-truck and travel the US for work.

  48. 348
    Floyd says:

    gavin: “As for ethanol blends, it all comes down to where the ethanol comes from. If it’s from corn in the US, emissions are basically the same as if it was pure gasoline (due to the fossil fuel use during production), if it’s from sugarcane in Brazil, net emissions are significantly lower.”

    There’s more to it than that. You have to factor in transportation costs, comparing US made ethanol that is transported with trucks and/or pipelines, versus Brazilian ethanol which is certainly transported further than the American ethanol, in this case by trucks or pipelines, and by ship. Also, I think I remember that sugarcane fields are burned as part of the harvest (please confirm or disprove).

  49. 349
    Hank Roberts says:

    Floyd, Google will be your friend. Just one hit from an easy search:
    Sweet! Sugarcane is Australia’s New Renewable Energy : TreeHugger
    For the first time in over 125 years sugar cane farmers, in one region of Australia will not burn their crop at harvest time. Instead they will ship the …

  50. 350
    Sekerob says:

    “you confirm or disprove”… how quaint. Where’s the support?

    As for US ethanol, the carbon footprint is 3 times that of regular fossil fuel. You disprove, no confirmation required.


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