Via a mailing list, Reason magazine has an article claiming that SUV’s are better for the environment than hybrid cars:
Spinella spent two years on the most comprehensive study to date – dubbed “Dust to Dust” — collecting data on the energy necessary to plan, build, sell, drive and dispose of a car from the initial conception to scrappage. He even included in the study such minutia as plant-to-dealer fuel costs of each vehicle, employee driving distances, and electricity usage per pound of material. All this data was then boiled down to an “energy cost per mile” figure for each car (see here and here).
Comparing this data, the study concludes that overall hybrids cost more in terms of overall energy consumed than comparable non-hybrid vehicles. But even more surprising, smaller hybrids’ energy costs are greater than many large, non-hybrid SUVs.
(I can’t say I’m not tempted to drop this link into this Making Light thread (scroll way down for a nasty little pissing contest about Hummers), but I’m trying not to be a Bad Person these days…)
It’s sort of telling that even the commenters on Reason’s own site find this analysis a little dodgy. I particularly like the inclusion of the cost of planning each vehicle, which I’m sure involves no hand-waving at all. The stated vehicle lifetimes are a nice touch, too– they give the Hummer a lifetime of 300,000 miles, but take the warranty value of 100,000 for the Prius.
I did want to comment on a couple of elements of the article that show up again and again in these articles, though, and will do so after the cut.
First is the oft-repeated claim that “in the real world — outside of the Environmental Protection Agency’s tax-payer funded testing sites — hybrids don’t deliver anywhere close to the gas mileage that the agency attributes to them.” We’ve had a Prius for a couple of years now, and this is news to me. Kate drives the hybrid back and forth to work (I can just barely manage to drive it to the store, if I need to), and averages something between 40-45 mpg in the winter, and 45-50 mpg in the summer, pretty much in line with the advertised values for her car (a 2003 Prius). The plural of “anecdote” is not “data,” and all that, but these statements about the mileage are directly contradictory to our experience with the vehicle (and those of other Prius owners I’ve talked to), which makes me question their validity.
The other thing that always drives me nuts about these discussions is the comparisons they make to other cars, as when a market researcher is quoted as to what people do when gas prices increase:
“They buy a Chevy Aveo,” says Spinella. “It delivers the same fuel economy as a Prius, but at half the price.”
(The mileage claim is, of course, based on the claim referred to above. The Aveo claims city/ highway mileage of 26/34 mpg, while the 2006 Prius claims 60/51 mpg)
This sort of comparison comes up all the time– the other popular form is to claim that you’ll never save enough on gas to make up for the higher price of the hybrid compared to some much cheaper little compact car. Which is true, as far as it goes, but then, I could also buy a pair of roller skates, and get even better gas mileage than the Prius. And, really, roller skates would be about as useful to me as an Aveo…
There’s a fundamental misunderstanding here about how people buy cars, or at least about how the people I know buy cars. The choice isn’t between a Prius and some subminiature toy car. If we hadn’t bought the Prius, we probably would’ve gotten something else in the same general price range– a Camry, or some such. When we were in the market for a new car, we figured out about how much we could afford (about the cost of a Prius), and planned to spend that amount of money. When we replace my car in six months or so (shortly before the warranty on the rebuilt transmission runs out), we’ll do the same basic thing.
The real apples-to-apples comparison, then, is between a hybrid and something that costs about the same amount of money as a hybrid, which might be a larger car with more options. The people buying Aveos aren’t people who would’ve been buying Priuses (Prii?) in the first place (unless they decided to buy two cars for the same money…).
It’s probably not worth getting too worked up about this– Reason is not, after all, a publication I usually consider reliable. I do get a kick out of the author praising Ford for backing off their promise to produce 250,000 hybrid cars by the end of the decade, though– it’s sort of fun to picture the same author thirty years ago declaring that tiny little Japanese cars will never make it in the US market…
I’m getting about 48 MPG in my Prius. Before I went to a different set of tires I was getting over 50. I don’t know anyone who gets Aveo type MPG in their Prius. Maybe if you’re dragging an anchor in Detroit in the dead of winter. But it’s the lifeime numbers that I find really bizarre. 100,000 miles for a Prius? I guess dragging that anchor shortens the car’s life.
It is good to find out that people are getting the expected mileage of out of their Prius. I didn’t really buy that claim either.
I don’t know if I agree with the statement that we should buy SUVs rather than hybrids, but I do agree with the argument that the total energy requirement of the car exceeds its gas mileage. I don’t feel qualified to critique the numbers but I am glad that research like this is getting done.
In reference to the claim they make that Hummers get 300,000 total miles while Prius’s get 100,000, I would note that they are arguing for total miles for all owners. I guess I think that is probably fair, although I expect that part of it is because Hummers have been on the market a lot longer. More people have had the opportunity to buy them used. Also, the hybrids have not been on the market long enough for the car makers to make them long lasting. I think that overall mileages for hybrids is likely to rise, so in the end their “Dust to dust” cost will decrease.
Just to add another anecdotal point…
My family owns two Civic hybrids. In warm weather, without air conditioning,
we get about 42-45 mpg. This should be compared to the EPA estimate of 51 mpg.
The fact that we commute about 3 miles each way accounts for some of the
discrepancy.
In the winter this drops to about 30mpg. Three miles is just not enough for the
engine to warm up, for the hybrid or for any other kind of car. With air conditioning
running the mileage is somewhere between 40 mpg (I only use the air on the drive
home, close to the heat of the day) and 34-35 (my daughter uses the air conditioning
all the time in the summer).
My experience with other car models suggests that they fall below the EPA estimates
by at least as much – especially when running air conditioning or driving short
distances in cold weather.
A colleague who commutes more than 30 miles every day gets very close to the EPA
estimate except when running the air conditioning.
If people drive the way they do in the DC area, racing to the next red light and slamming on the brakes, they’re not going to get the official gas mileage, either. Meanwhile, I drive with an eye to conserving gasoline and once got 80 mpg in my wife’s Honda Insight on an all-highway trip from just outside the Washington Beltway to the bottom of the Baltimore Harbor Tunnel.
Forget about hybrids. Start saving up for the Tesla Roadster! For only a $100K you’ll get a quiet EV that goes from 0 to 60 in 4 sec and a 250 mile range with equivalent of 135 mpg.
This company has been getting a lot of press around here in the Bay Area lately. As Silicon Valley’s first auto company, and with the backing of the Google Guys, there’s some of expectation that this may be the start of a new EV industry out here, independent of the big Detroit car makers. Who knows…
Glad our Governator liked it (Quote from a cnet article):
“It’s terrific,” the governor said, before speeding off with his two kids and a bodyguard in an SUV after test driving the car. Stupid Hummer!
diesel’s get the same gas mileage as a prius (for a similarly sized car obviously). So hopefully Toyota is looking into designing their own or buying one from Europe to mate with the Prius hybrid technology. The greatest part about it is since diesels have such great low rpm torque, you could in theory run the diesel only to charge the battery, always use the electric motor to actually drive the car and have the diesel engine only run at its optimum rpm for fuel efficiency to charge the battery.
I could see getting 150-200MPG from diesel hybrids, more if Toyota is looking at what the Prius hackers are doing.
Is diesel better or worse on the emissions front? I know the diesel exhaust makes me feel sick a lot faster than regular gasoline exhaust, but I’m not sure what relation that has to actual emissions.
As for the electric roadster, given that I could buy a house for $100K, I think I’ll be waiting for the price to come down a little before I go there… I realize that Silicon Valley real estate prices probably put this more in the range of the usual car:house price ratio, but really.
Diesel passenger cars are still a polluter, based off what I’ve read. CA has such tight emission requirements that it’s pretty hard to buy a diesel car that meets the standards of the California Air Resources Board. Only 5 states adopt the CA requirements and soon the EPA will be adopting the T2B5 standard (which is aligned with CAs) for all 50 states. I have a feeling that as automakers begin to incorporate cleaner diesel engines this will be reflected as a sharp increase of the sales price. Will that 30% mpg efficiency improvement be cost effective then?
Btw, it’s ridiculous what you see out here in the Bay Area with SUVs, especially Hummers. Those people who actually are paying $1M for a 2000 sq.ft. homes are the types not only shelling out for the expensive gas guzzlers, but likely to be the types to purchase new Hummers before they even hit 100,000 miles in their old ones.
Diesel engines produce more particulates of a certain size range and, if not controlled, more NOx, than spark-ignition engines. They produce less unburned hydrocarbons since they typicall burn with lean mixtures. That’s also part of the problem with NOx. There is some question about whether the particulate sizes are as dangerous as the smaller particulates produced in spark-ignition vehicles, but apparently EPA regs do not reflect any of that uncertainty. Diesels should produce less CO2 since they use less fuel to go a given distance, assuming some similarity in size and performance. Diesel engine technology is in a state of flux now because of new pollution requirements. The net result, at least for the short term, is probably that they will get lower fuel economy than before and will cost more. But this was also the case for gasoline engines when pollution regs first came into effect. All that said, my 2001 VW diesel gets 48-50 mpg overall, but I do not do a lot of short-distance driving.
I am not confident of the calculation of life-time cost of a large SUV being higher than for a hybrid. I also consider it absurd to talk about a Hummer having a 300,000 mile lifetime. How many vehicles are driven that far? Not too damn many. On the other hand, vehicles with diesel engines often do go significantly over 100,000 miles. On the other other hand, although Toyota has said the Prius batter pack will last the life of the car, I am not certain what that life is, or how much a new battery pack would cost. I doubt they expect a Prius’s life to be 300,000 miles.
But, if you want to talk about overall cost, I think it leaves the conversation open to costs other than those directly involved in producing, driving, maintaining and junking a vehicle. For example, if US drivers continue to demand more petroleum fuels than we can provide for ourselves, the US will continue to be compelled to insert its nose into dangerous regions of the world. How do you count the ~$300B estimated to have been spent in Iraq (not to mention lives), spent because we must involve ourselves in the Middle East?
To get an idea of the specific impacts of the Hybrid technology, I extracted their for numbers Civics vs Civic Hybrids from their report.
Civic Hybrid:
-Lifetime: 113,000 miles
-E Cost/mile:
Total: $3.238
Fuel: $0.076 (2.4%)
Maintenance/Repair: $0.166* (5.1%)
Accident Repair: $0.084* (2.6%)
Design/Development E Cost: $0.234* (7.2%)
Manufacturing E Cost: $0.117* (3.6%)
Support E Cost: $0.011* (0.3%)
Transport E Cost: $0.006* (0.2%)
Dealer E Cost: $0.020* (0.6%)
Recyclable Parts E Cost: $1.21* (37.4%)
Disposable Parts E Cost: $1.46* (45.1%)
Reusable Parts E Cost: $0.307* (9.5%)
Civic:
-Lifetime: 178,000 miles
-E Cost/mile
Total: $2.420
Fuel: $0.128 (5.3%)
Maintenance/Repair: $0.075* (3.1%)
Accident Repair: $0.041* (1.7%)
Manufacturing: $0.055* (2.3%)
Design/Development: $0.052* (2.1%)
Support E Cost: $0.004* (0.2%)
Transport E Cost: $0.004* (0.2%)
Dealer E Cost: $0.009* (0.4%)
Recyclable parts: $0.696* (28.8%)
Disposable parts: $1.427* (59.0%)
Reusable parts: $0.122* (5.0%)
Deltas (Hybrid – Civic):
-Lifetime: -75,000 miles
-E Cost/mile
Total: $0.818
Fuel: -$0.052 (-6.4%)
Maintenance/Repair: $0.091 (11.1%)
Accident Repair: $0.043 (5.3%)
Manufacturing: $0.062 (7.6%)
Design/Development: $0.182 (22.2%)
Support E Cost: $0.007 (0.9%)
Transport E Cost: $0.002 (0.2%)
Dealer E Cost: $0.011 (1.3%)
Recyclable parts: $0.514 (62.8%)
Disposable parts: $0.033 (4.0%)
Reusable parts: $0.185 (22.6%)
* calculated by dividing their lifetime E Cost by lifetime miles. %s are calculated based on their total numbers, which don’t seem to match the sums of the categories, so they don’t add up to 100% (and it’s more than could be accounted for by rounding error – either them or I messed up somewhere).
One of the most common complaints about the report’s methodology is that it includes design and development, which are obviously going to be higher for newly introduced technologies, but they only account for a fraction of the differences. More important seems to be the lifespan, which is in the report as lower for the Hybrids. I think they are also overestimating the energy costs for parts, but I don’t know enough about their methods to say whether they’re accurate (the report doesn’t give that much detail, but their method for recyclable parts sounded like it would overestimate thee energy costs by not including substitution of recycled material for new material in other industries). Overall, if there aren’t any glaring methodological shortfalls in how they arrived at their numbers, they may have a point about hybrids not necessarily having a better overall energy footprint than comparable conventional models. CNWMR says it’s going to release the details of its analysis later, so it will be interesting to pick it over when it does.
The lifetime factor really seems to account for the vast majority of those differences. Scaling the hybrid cost numbers by 113/178 (giving the two cars equal lifetimes in terms of miles) cuts the difference from “design/ development” by almost a factor of two (from $0.182 to $0.097), and the “recyclable parts” difference by almost an order of magnitude ($0.514 to $0.072). The overall cost/mile would drop to $2.06, a moderately significant improvement over a regular Civic.
That really jumps out as the most dodgy point of this analysis.
Ack!
Did anyone bother to read the report? It’s just total gibberish. They don’t publish their method, they don’t systematically describe their model. And everyone is assuming that this marketing firm, yes a marketing firm, is telling us the truth?
This doesn’t even pass the smell test. If it was less economical to generate a hybrid than a Hummer, than it would kind of have to cost more wouldn’t it? The analysis fails from the start. And in terms of maintainance costs, whatever, do the prius drivers really end up spending 40k more over the life of their car? Finally, they include recycling costs (or so they say, the comment on what they included in their methods but not in a systematic way) but does a consumer realistically have to pay for these things? Are we to believe that to recycle a 1/2 ton prius costs as much as recycling materials from a 2-ton Hummer? Or that this is even done? The cars have been on the road for what, three years?
This entire study raises billions more questions than it answers, especially because they provide no information that would allow one to peer review exactly what they did. I’ll believe it when someone, other than a market-research firm, conducts this study, it is peer-reviewed, and finally published somewhere other than their own website (and Reason, home of libertarian creeps).
It’s been awhile since I looked at Making Light. It still reads like Jabberwocky.
quitter – Well, I obviously did (that’s how I made my Civic vs Hybrid Civic comparision). However, you can’t just add up the numbers and compare them with retail values – the unit isn’t actual dollars – I think it is the equivalent of the cost of getting the energy used by burning gasoline (one of several places where the report lacks clarity). I’d much rather that they gave the energy requirements in BTUs so they could be checked against aggregate numbers.
I think you’re misunderstanding the recycling E cost number – I’m pretty sure the author meant to use it to describe the energy expended in the entire lifetime of the parts that go into the car that are expected to end their life by being recycled, which makes a lot more sense in the context of the other values.
Anybody know of any sources for lifespan numbers other than the manufaturer and the report? Googling alone doesn’t turn up anything useful.
I’ve only scanned the Reason article, but Edmunds published a piece last year dismissing hybrids as costlier-than-advertised. (I swung at that pitch here.)
Neither article mentions social, health, or other costs associated with high fuel consumption/ high pollution generating vehicles. Hybrid technology excels at its initial mission: to reduce unhealthful tailpipe emissions while enhancing efficient transportation value to consumers.
Neither Reason nor Edmunds mentions the costs associated with geopolitical strife from competition for non-renewable energy– whether that means competition to monopolize energy resources, or the human, social, resource, and environmental degradation that accompanies war. Our national debt, to a large degree the result of our energy policy, contributes its share to the costs of selecting gas-guzzlers over cleaner, more efficient technologies.
If valid, credible fuel-use cost comparisons aren’t enough to convince retro-skeptics like Reason or Edmunds, then the additional economic sequelae of planetary climate change from pollution and fuel consumption should factor into their calculations.
By the way, my little Prius passed its sixth birthday with my family this week, ticking up 105,000 trouble-free miles with a lifetime fuel use average of 45.1 miles per gallon.
I’ve read most of it now, and someone has to point to me where in this report are their goddamn methods?
The entire organization of the report is schizophrenic, the introduction looks like it’s assembled from spare parts, the methods are referred to piecemeal as if in passing. The data that finally gets presented doesn’t make any rational sense. Why is anyone even taking this seriously? The whole thing smells of being an unprofessional hack-job.
Why is this piece of marketing research being discussed as a serious scientific article? It isn’t peer reviewed, it has no clear methods that would allow one to replicate or understand the numbers, it says things that just sound stupid. Further, there are clear indications that there are biases in these numbers. Does anyone else see that the “estimated life miles” for all the hybrids are one-third that of the SUVs on the list? The Escalade has an average of 234,000? The excursion 269k? THe Suburban 270k? The Tahoe 268k? Are they kidding? Average? Compared to a Prius or Honda Civic hybrid numbers at around 100k? The Camry gets 200k, the same as the H2? In fact, if you look at the data it seems all the SUVs are given pretty outrageous mileages. Maybe, just maybe, that means that the denominator in their equation of cost just got a lot bigger thus falsely inflating the cheapness of these bigger cars? Maybe dividing all the cost per mile for these huge freaking cars by a factor of three is how they came up with this absurd conclusion?
Given we have no idea of their calculations, how could one know? But I smell bullshit all over this report.
I think the problem here is that scientists really like hearing about inversions. When something everybody takes for granted as being true is actually proven false. I know this because I love learning things like that too. However, I don’t think this report is a viable piece of information to hang your hat on, it just smells like BS, and people who are publishing things like this should at least have a cursory outline of their methods and equations.
Why is this piece of marketing research being discussed as a serious scientific article? It isn’t peer reviewed, it has no clear methods that would allow one to replicate or understand the numbers, it says things that just sound stupid.
I don’t think anybody’s really treating it as solid scientific research. I’m certainly skeptical of the analysis and conclusions, as I hope my post indicated, and the Reason piece is more of an opinion column than a serious news article.
I blogged about it here because, well, environmental issues are a continuing topic of discussion here on ScienceBlogs, and I thought it might be of interest to people who hadn’t seen it. I imagine Jake did the same, but you’d have to ask him.
Sorry, I didn’t mean to indicate that you personally had swallowed this claptrap, but based on the way Jake wrote about it it sounds like he drank the Kool-Aid. I’m pissed that people are reposting their “data” as if it is real, or discussing this as if the findings are factual, like we would with any scientific paper in which you always believe the data, but not necessarily the interpretation. I don’t believe we should act as though the data are even real, or a valid topic of discussion because this report from a marketing firm, the methods are not public, the report is written in a disorganized and idiotic fashion, and I think there are clear examples of bias in the so-called data they present. Not to mention when Mattiv tries to just make the numbers add up they don’t fit. It should also be obvious that if they’re doing cost per mile that in each case the hybrids have the lowest average lifetime miles (probably because the cars are new to the market – if not because the authors are outright lying) and all the comparisons using this number in the denominator are obviously going to inflate the relative cost of the hybrids.
I guess I’m pissed at Reason, big surprise. There’s a misnomer if I’ve ever heard one. Does anyone else find it a little bit irritating that they name their journal that? Like anything they don’t believe is unreasonable, it’s so arrogant. Reason. Feh. I’ve seen so much crap come out of that libertarian rag. Like this turd of a report.
Re : Diesels..
Well, I get around 42mpg (US gallons) real world in my Peugeot 406 diesel. Certainly, particulates are not a problem with pugs since they developed the particle trap technology. Given the fairly extreme milage associated with diesels, I also suspect it will beat most SUVs (never mind hybrids) on milage terms as well.
Plus it handles miles better than either hybrid or SUV, always a plus..
Re:8 Actually, a lot of modern eurpoean diesels have a problem with US quality fuel – the technology is already there and I believe that imnprovements in fuel quality in the US will allow the introduction of the newer diesels. Then it’s just a matter of public perception.
Nothing new. Hard Green by Peter Huber, said similar things, although it was a general critique of how costs are assessed. Many seemingly green ideas are in actuality worse for the environment.
We just bought a 2006 Prius back in May. My wife, who does all highway driving, gets 52 mpg consistently. I get less when I drive it (about 45), but I drive mainly on roads with 45 mph speed limit and traffic signals every few blocks. Nobody rates a car for that kind of driving.
In 2006 there is a federal tax credit for hybrid cars of up to $3500, scaled by mileage. The Prius qualifies for $3100. In addition, my state (PA) has a $500 rebate. Taking $3600 off the price of the Prius brings its overall price pretty close to what an equivalent, non-hybrid would be.
I also don’t buy that hybrids will suffer from reduced longevity. The new technology in the hybrid actually has relatively few moving parts. An electric motor plus the solid state circuitry to control the power plant should have a shelf life vastly longer than a conventional gasoline-powered engine. There is no reason to think the Prius will last any shorter than an equivalent non-hybrid Toyota. Yes, the batteries will eventually go bad and have to be replaced, but by that time pluggable hybrid technology conversion kits may make it an upgrade.
In any case, we love our Prius, and I doubt I’ll ever buy another conventional automobile again.
Ni hao! Kannichi Wa!
The diesel engine is the backbone of the American economy, 12% of our total fuel consumption, transports 70% of the nation’s goods at $6 trillion value annually, 51% of our GDP. 18 million tons of freight and 14 million people transported daily.
All this detailed talk about alternatively fueled personal autos is nice, but likely of relatively little consequence except to ease consciences about using fuel and creating pollution for personal reasons. We can give up the personal auto fueled by gasoline, ethanol, hybrid techniques of various types before we can give up the diesel that distributes food, housing materials, energy, and modern living at current and future population densities. We can adjust on a personal level to gasoline, alt fuel shortages and rising costs by going to walking, bikes, car pools, mass transit, but industry and commerce simply cannot and industry runs on diesel.
Logically, personal autos should follow suit, but 1% of US autos are diesel whereas some countries in Europe are greater than 25%. The Rudolph Diesel engine was the first most versatile and economic performing engine invented, and still the concept that should be perfected. Eventually it should be able to burn about any source of reduced (hydrogenated) carbon although current quality demands:
triglycerides + methanol/KOH = fatty acid esters (biodiesel) + glycerol (about 1 gallon oil gives one gallon fuel).
Feedstock and triglyceride source becomes the next challenge? Here’s the stats on current feedstock availability in the US.
The Department of Energy estimates U.S. biomass crop potential at around 160 million tons a year that could save one million barrels of oil a day. Consumption is currently around 21 million per day. Before this redundant study above it is clear the US cannot grow to diesel independence currently with the current amount of arable land say with soy as the current available prototype (soybeans have food value, oil is sort of a by-product). However, there are much more productive oil producing plants, but they have less food or other value. Examples are jatropha, which can be grown in arid regions where edible agriculture is limited, can produce 200 gallons of oil per acre. Coconut produces 300 gallons of oil per acre of trees, and palm oil is the highest at 650 gallons per acre (edible oil now mostly used as food additive and in cosmetics). Soy produces 75 gallons of oil per acre and canola (flax seed, most popular in Europe) 150 gallons per acre.
These are all conventional feedstocks grown in diverse places around the world, largely for other purposes than fuel. But here is the ultimate step. Bring into production the world’s great mass of non-arable lands by current technologies that does not compete with current high yield foodstock production with organisms that mainly made fossil fuels in the first place in aquatic, even saltwater environments. There are numerous localized technical problems, but the basic research and proof of concept has mostly been done.
Now is only the will to implement. Algae or similar organisms genetically engineered for whatever rate-limiting property we want as triglyceride production, cold or heat resistant, salt or contaminating microorganism resistant, waste and sewage as nutritive source. Moreover, high density growth needs high density carbon dioxide and heat (particularly in cold deserts at night) so such ponds can be used as scrubbers for coal fired plants and heat sinks for nuclear cooling water. What about the Great Salt Lake? Or barren salt water desert and tropical countries turned into the oil producers of the world? Global warming could even be a boon since night time temperatures can be limiting to production. Think big, think global, like Big Al, we can do it.
MOTYR
From the DOE and USDA:
Energy Balance/Energy Life Cycle
Energy yield Net Energy (loss) or gain
Fossil Gasoline 0.805 (19.5 percent)
Fossil Diesel 0.843 (15.7 percent)
Ethanol 1.34 34 percent
Biodiesel 3.20 220 percent
*Life cycle yield in liquid fuel Btus for each Btu of fossil fuel energy consumed in production.
I found this link regarding the life of Prius batteries. It’s anecdotal, of course, but at least it’s encouraging.
http://www.hybridcars.com/hidden-costs.html
In short, the linked article talks about people driving their hybrids a lot more than 100,000 miles with no apparent degradation of battery performance. It also talks about dealerships misdiagnosing terminal corrosion for battery failure, a possible explanation for early battery failure.
I read the Reason article, which seemed like so much hot air. Where is the actual study, including the numbers used? I would be particularly interested in what numbers they used for a gallon of gas. If the study is more than 6 months oold, they probably used numbers lower than the current retail price. Remember the goold old days, when gas was only $2 per gallon? Also, in the future, I expect the price of gas (and petroleum in general) to rise relative to other commodities, since it is a nonrenewable resource.
And global warming – how did they calculate the cost of that and the impact of different vehicles on it?
I asked a friend about mileage in his Prius: