Prius vs. Hummer Analysis Debunked
by Eric Richard
Many people have seen or heard about the articles going around that say that “owning a Hummer is better for the environment than owning a Prius.” This all stems from the report called “Dust to Dust†and a follow on commentary called “Hidden Cost of Driving a Prius†by CNW Research. This report then seems to have gotten legs when a column was run in The Recorder, the paper for the Central Connecticut State University.
I think for most of us, our initial reaction was, “Hmmm… That sounds odd. I wonder how they came to that conclusion?”
For those who dug a little deeper, you found that, one of the most controversial aspects of this report is that it assumes as lifespan of 100,000 miles for the Prius and a lifespan of 300,000 miles for the Hummer. This winds up having immense implications on the rest of the analysis since it basically means that you need to buy 3 Priuses to travel the same distance as 1 Hummer. So, the real analysis says that “owning a Hummer is better for the environment than owning three Priuses.”
Since this is the most glaring issue that gets raised by this report, the folks at CNW Research have put out a paper called “Why 100,000 Miles for Prius?” that explains the rationale for this figure.
Reading this document is quite fascinating and I think points to the ludicrousness of the Prius vs. Hummer analysis.
If you read through their document, they basically make the point that Priuses have a shorter lifespan (in miles driven, not time) for the following reason: People who drive Priuses (especially people who drive first generation Priuses) drive less than people who drive other cars.
Yup! That’s the real problem. Confused? Read on.
The key point here is that this is a factor of the people’s driving habits and not of the car itself. This basically says that if you were already inclined to drive small amounts, then you are inclined to buy a Prius. If you were inclined to drive large amounts, then you wouldn’t be inclined to drive a Prius.
This is all probably completely true. But, how does that affect the analysis?
Well, if you start with the assumption that Prius owners only drive ~7,000 miles per year, then you can do the math and figure out that it will take about 15 years for that driver to get to 100,000 miles on the car.
And then you ask the question, “Is someone likely to keep the car for more than 15 years?”. Since the answer is no, you thus put the “effective” lifespan of the car at 100,000 miles. Not because the car couldn’t go further, but because the person didn’t drive it more.
Let me just restate that to be clear. The report is not saying that Priuses can only drive 100,000 miles. In fact, the report makes absolutely no statement on how far Priuses could be driven. What the report says is that Prius drivers tend to drive so little that by the time they’ve driven 100,000 miles, they are likely to get rid of their car.
Just to drive this point home, if that same car owner traded in their Prius for a Hummer, you’d make the exact same argument about the Hummer; you’d say that it had a life expectancy of 100,000 miles.
Or, looked at from the other perspective, the report says:
If the Prius were driven the American average of 13,000 miles per year, it would hit the 100,000 mile mark in 7.6 years, well within its attractive (financially and technologically) useful life span. In 10 years, again about the maximum for ground-breaking technology, it would have registered 130,000 miles. Mechanically, there is no logical reason for the Prius not to last 130,000 miles or more.
In fact, the report goes on to say that, “The latest data shows Prius owners are driving more than early Prius owners and the use of the vehicle is becoming a primary means of transportation in a household rather than a novelty,” although it does say that “the average annual mileage, outside of certain southern-tier states, remains barely above 7,000 per year.”
As more and more people drive Priuses and use them for mainstream driving, this entire analysis is going to go to the wind. As an example, my Prius is about 3 years old and I am about to hit 60,000 miles. If I drive my Prius for another 3-5 years, I will blow through their numbers.
The report also points out that much of the reason that the Prius fairs poorly compared to the Hummer is that “much of the design, development and manufacturing energy costs [for the Hummer] are spread across more than just this single model. … The platform, power train and other mechanical components are shared with a variety of other GM products and have a significantly longer post-disposal life in the replacement market.”
Again, this was true for the early Prius models. For example, the first generation Prius had special “fuel efficient” tires. But, in the second generation, they replaced these tires with “normal” tires because people wanted better road handling at the cost of fuel efficiency.
In addition, as Toyota installs the hybrid synergy drive in more of their models, the Prius will start to get the same efficiencies as the Hummer.
More than likely, you could make this same claim about the cost of producing any new car or car with new technology. For some period of time, you are experimenting and, thus, the costs are high. But, then once they go mainstream, the costs decrease.
So, looking at this full report, the take away messages are that “Cars based on new technology are more expensive initially than cars based on mature technology” and “When a car has a niche market of environmentally conscious consumers, they aren’t likely to drive a lot.”
That’s pretty much all you can take away from this analysis.
And while the result of this analysis is that first generation Priuses fit into both of these categories, the key point is that both of these arguments are based on a point in time and are changing and neither of these arguments have anything to do with the technology or design of Prius in particular (except to the extent that its design attracted people who don’t drive a lot in the first place).
You could put any car in this same analysis and get the same results if it was based on new technology and people didn’t drive it much.
As people drive Priuses more and as the technology under Priuses become more and more mainstream, the entire underpinnings for this report are going to evaporate and you will ultimately get to the steady state analysis where you can accurately compare the environmental footprint of the Prius to other cars.
Thus, I think it is fair to say that this report is really just a load of hooey and shouldn’t be given any real merit. (Of course, I don’t think any of you were giving it merit, but now you at least know why. =)
P.S., I am happy to see that the folks at CNW Research published this document in response to a “bloggers’ frenzy” over this issue. Of course, that makes it sound like this was all an imaginary issue in the blogosphere, completely discounting the impact of the “Hidden Cost of Driving a Prius†document that they themselves wrote.
on May 12th, 2007 at 7:52 pm
From Nancy Kramer of Sustainable South Shore:
Hi all, one of the first Prius owners from Hingham has over 200,000 miles. He is usually at our Sustainable Living Festival, each year, but was away, this year.
on May 15th, 2007 at 3:56 am
Thank you for publishing this.
If you go back to when CNW’s report was first published in April 2006, you’ll see that they initially justified the 100k lifespan for a Prius quite differently.
For instance, if you listen to the interview with Art Spinella here:
http://www.thewatt.com/article-1083-nested-1-0.html
(interview starts at 12:30, the part I’m paraphrasing is at 24:40)
you’ll hear him state that 100k is Toyota’s own lifespan estimate for the Prius, and that obviously if you *could* drive it further, that would have a major affect on its total energy cost.
That’s quite a different justification from the one CNW later proposes in the paper you cite. For one thing, we’re now talking not about how far you *could* drive a Prius, but about how far you are *likely* to drive a Prius. That’s an entirely different question, and you’d think such a change would affect all the study’s results across the board. (Let’s ignore the question for now about how many people are likely to drive a Hummer 300k over any amount of time at all.)
Now, the fact that the source/justification for this piece of data could change so radically, while the data value changes not at all, raises very, very serious questions about all the data in the entire study. This starts to look a lot like data in search of a justification, rather than a solid justification for data. In other words, like this study is working backwards from a desired result.
I wish someone would once and for all definitively bury this report. But it would make a fascinating graduate student study, to track how this hugely counter-intuitive and unvalidated study entered the media without any critical analysis whatsoever and has echoed about ever since, most recently even turning up in a Washington Post Op-Ed piece by a respected columnist.
on May 15th, 2007 at 4:06 am
Can you point me to the Washington Post Op-Ed? I think someone at work may have referenced this recently, but I hadn’t been able to find it?
on May 15th, 2007 at 5:15 am
Shockingly, it was George Will!
Fuzzy Climate Math
[FINAL Edition]
The Washington Post - Washington, D.C.
Author: George F Will
Date: Apr 12, 2007
Section: EDITORIAL
Document Types: Commentary
Text Word Count: 758
Copyright The Washington Post Company Apr 12, 2007
In a campaign without peacetime precedent, the media- entertainment-environmental complex is warning about global warming. Never, other than during the two world wars, has there been such a concerted effort by opinion-forming institutions to indoctrinate Americans, 83 percent of whom now call global warming a “serious problem.” Indoctrination is supposed to be a predicate for action commensurate with professions of seriousness.
For example, Democrats could demand that the president send the Kyoto Protocol to the Senate so they can embrace it. In 1997, the Senate voted 95 to 0 in opposition to any agreement that would, like the protocol, require significant reduction of greenhouse gas emissions in America and some other developed nations but that would involve no “specific scheduled commitments” for 129 “developing” countries, including the second-, fourth-, 10th-, 11th-, 13th- and 15th-largest economies (China, India, Brazil, South Korea, Mexico and Indonesia). Forty-two of the senators serving in 1997 are gone. Let’s find out if the new senators disagree with the 1997 vote.
Do they also disagree with Bjorn Lomborg, author of “The Skeptical Environmentalist”? He says: Compliance with Kyoto would reduce global warming by an amount too small to measure. But the cost of compliance just to the United States would be higher than the cost of providing the entire world with clean drinking water and sanitation, which would prevent 2 million deaths (from diseases such as infant diarrhea) a year and prevent half a billion people from becoming seriously ill each year.
Nature designed us as carnivores, but what does nature know about nature? Meat has been designated a menace. Among the 51 exhortations in Time magazine’s “Global Warming Survival Guide” (April 9), No. 22 says a BMW is less responsible than a Big Mac for “climate change,” that conveniently imprecise name for our peril. This is because the world meat industry produces 18 percent of the world’s greenhouse gas emissions, more than transportation produces. Nitrous oxide in manure (warming effect: 296 times greater than that of carbon) and methane from animal flatulence (23 times greater) mean that “a 16- oz. T-bone is like a Hummer on a plate.”
Ben & Jerry’s ice cream might be even more sinister: A gallon of it requires electricity-guzzling refrigeration and four gallons of milk produced by cows that simultaneously produce eight gallons of manure and flatulence with eight gallons of methane. The cows do this while consuming lots of grain and hay, which are cultivated by using tractor fuel, chemical fertilizers, herbicides and insecticides, and transported by fuel-consuming trains and trucks.
Newsweek says most food travels at least 1,200 miles to get to Americans’ plates, so buying local food will save fuel. Do not order halibut in Omaha.
Speaking of Hummers, perhaps it is environmentally responsible to buy one and squash a Prius with it. The Prius hybrid is, of course, fuel-efficient. There are, however, environmental costs to mining and smelting (in Canada) 1,000 tons a year of zinc for the battery- powered second motor, and the shipping of the zinc 10,000 miles — trailing a cloud of carbon dioxide — to Wales for refining and then to China for turning it into the component that is then sent to a battery factory in Japan.
Opinions differ as to whether acid rain from the Canadian mining and smelting operation is killing vegetation that once absorbed carbon dioxide. But a report from CNW Marketing Research (”Dust to Dust: The Energy Cost of New Vehicles from Concept to Disposal”) concludes that in “dollars per lifetime mile,” a Prius (expected life: 109,000 miles) costs $3.25, compared with $1.95 for a Hummer H3 (expected life: 207,000 miles).
The CNW report states that a hybrid makes economic and environmental sense for a purchaser living in the Los Angeles basin, where fuel costs are high and smog is worrisome. But environmental costs of the hybrid are exported from the basin.
We are urged to “think globally and act locally,” as Gov. Arnold Schwarzenegger has done with proposals to reduce California’s carbon dioxide emissions 25 percent by 2020. If California improbably achieves this, at a cost not yet computed, it will have reduced global greenhouse gas emissions 0.3 percent. The question is:
Suppose the costs over a decade of trying to achieve a local goal are significant. And suppose the positive impact on the globe’s temperature is insignificant — and much less than, say, the negative impact of one year’s increase in the number of vehicles in one country (e.g., India). If so, are people who recommend such things thinking globally but not clearly?
on May 24th, 2007 at 9:54 am
My wish has been granted. Here’s an excellent compendium of the major ways in which CNW’s report is utter cr*p:
http://www.pacinst.org/topics/integrity_of_science/case_studies/hummer_versus_prius.html
It’s short and fun to read.
But I’m still waiting on someone to describe how this piece of junk got such legs — that’s the real story here, how utter garbage penetrated so deeply into the collective consciousness. The web makes it fairly easy to trace an outline, maybe for the first time.
Jon
on May 24th, 2007 at 5:49 pm
I suspect that this story got legs the way urban legends always have. Whether it is Al Gore inventing the Internet or Catherine the Great dying in a bizarre tryst with a horse, urban legends are simply gossip and myth we all know. You come up with a story that plays on people’s fears or desires. You make it just believable to be true. And, voila! Instant urban legend.
I googled “dust to dust” and “cnw marketing”, and had a hard time finding any credible news sources that covered this story. Instead, I found lots of blogs and message boards where people were discussing a single, satirical editorial from the Central Connecticut State University newspaper. A few papers did pick this up, but by and large, people heard about it through the Internet grapevine.
Perhaps the Internet shortens the gestation period of these sorts of stories, but ultimately, this is nothing new. It’s all just gossip that either validates peoples feelings (I knew I hated those uppity Prius drivers for a reason!) or fears (Why is it whenever I try to do something good for the enviroment, it turns out to make things worse?)
on May 24th, 2007 at 5:51 pm
Hmm… My Al Gore link didn’t work. The debunking of that myth is here.
on May 26th, 2007 at 1:16 am
Actually, for a truly comprehensive debunking of the faulty “Dust to Dust” report, take a look at the brand new analysis from the Pacific Institute’s Integrity of Science initiative:
http://www.pacinst.org/topics/integrity_of_science/case_studies/hummer_versus_prius.html
on May 26th, 2007 at 9:41 am
Vicki,
Thanks, good points about commonalities of urban myths.
I think the reason you couldn’t find credible news sources that published the myth is just the bulk of commentary that has succeeded it. This bogus report is extremely widely cited. I’ve been following this since the original release in April 2006, though — I read car blogs — and this myth is on its third major wind right now. I know it was reported in US News & World Report, The WSJ, I’m pretty sure Forbes and the NYT soon after its original release (as well as in a host of more local publications). It fades in the real media but bounces around the Internet endlessly and then winds up in the press again, fades again, comes back, etc. In this latest wave, the fool in Connecticut rapidly led to the myth’s appearance in a George Will Op-Ed in the Washington Post. And this is well after the thing has been seriously and repeatedly denounced as obvious nonsense.
Guess you can tell, I’m still astounded. Mostly I guess at how ready the media is to pick it up again without even the most cursory sort of fact checking. What else is getting spread about as fact on the same terms?