Which is better for the environment? A new Prius or a used gas guzzler?

August 10, 2012 10:15 AM

I have an ongoing (friendly) disagreement with a guy I know. He drives a Toyota Prius because it's "better for the environment" than buying, say, a new Subaru Outback. Fine. I get that. But my argument is that it would be even better for the environment if he were to buy a used Subaru Outbook. I've never run the numbers, but it seems to me that if you were to buy the most gas-guzzling of used cars, the fact that you're not causing a new vehicle to be produced would make up for the lack of fuel efficiency. Can you help support my position? Or, alternatively, give me solid numbers as to why I'm wrong? Are there websites that have run analyses on this sort of thing already?
posted by jdroth to grab bag (24 answers total)

It seems to me there are lots of ways to measure 'better for the environment'. For example, emissions matter the most if we are talking purely about air quality in the city where you live. If we are talking about just pure pounds-of-co2 emitted into the atmosphere then I agree with you that higher MPG alone would take a long time to match the co2 costs to extract more metal, manufacture etc.

This article seems to try an answer the question.
posted by H. Roark at 10:22 AM on August 10, 2012

This article seems to say what you are saying. It seems to be a pretty googleable topic, actually. I don't think there's any question that production of a new vehicle involves a pretty substantial CO2 output.
posted by J. Wilson at 10:26 AM on August 10, 2012

It's probably impossible to say for sure, as there are so many variables.

For example, by buying a used Subaru or any car with bad mileage, you are directly supporting the market for those cars. After all, new car prices are partially dependent on how much they can be sold for. By buying a used Subaru, you are making the purchase of new Subarus more attractive (by supporting the used market). And, by buying a Prius, your friend can then sell it to someone else when he's done, and contribute to that person being incredibly green. Etc. etc.
posted by zachawry at 10:27 AM on August 10, 2012 [1 favorite]

But your neighbor wanted to buy that used Subaru Outback. Now he has to buy a new car. That's a ridiculous simplification, of course, but it's worth noting that your car purchase doesn't exist in a vacuum.

This article offers some info about hybrid car production waste, which apparently is higher than conventional cars, and approximately 10 to 20 percent of a car's estimated lifetime emissions.
posted by acidic at 10:31 AM on August 10, 2012

Here's another article that makes the case that the CO2 emissions from manufacturing a car are comparable to the lifetime CO2 emissions from driving the car, so from a carbon perspective we should drive all the cars we currently have until they're dead.

That also ignores the non-carbon environmental impact from car manufacturing (like mining for metals) that are associated with production but not driving. I think you're right. If the problem is new hybrid vs. new non-hybrid it's a different argument.
posted by no regrets, coyote at 10:59 AM on August 10, 2012

This might makezachawry's comment clearer:

"My friend wanted to buy a new 500 square foot home. But I argued that he should buy a used house. Even the largest, draftiest mansion would be better for the enviroment, because the fact that you're not causing a new home to be produced would make up for the extra heating and A/C costs."

That's clearly wrong, because if you don't buy the mansion, someone else will, and then there will be one fewer mansion constructed.

It's often clearer if you remember that you when you buy a car, you don't care about the car, you care about the transportation services provided by the car.
posted by Mr.Know-it-some at 11:00 AM on August 10, 2012

The batteries of Prius's are only warrantied for 8 years or 100,000 miles - so it's not really likely it will be able to be resold. I have a Prius, but it's mostly because my dad sells them and I was able to get a good deal.
posted by eq21 at 11:01 AM on August 10, 2012

From acidic's link: But do the environmental impacts of hybrid vehicle production outweigh the long-term benefits of driving a cleaner running automobile? That answer is a resounding "no."

Obviously what you do is get your friend to buy a new Prius, then later on you buy it used from him used and blame him for the initial hit.

There's also the angle of supporting a market for greener technology. If all the people like your friend all bought used Subarus, would the net effect encourage greener cars in the future? Surely a used Prius would be better than a used Subaru, and used cars gotta come from somewhere.

I think sometimes the greenest thing to do overall will not be the greenest thing as determined to be the local minimum of a simplistic emission counting function.
posted by fleacircus at 11:02 AM on August 10, 2012 [2 favorites]

To add to my previous comment, the batteries tend to last around 8 years
posted by eq21 at 11:02 AM on August 10, 2012

I think you are looking for a cradle to grave type analysis, so perhaps googling that will help. A few years back an article by CNW Marketing Research, arguing what you are arguing about the energy costs of a Prius, raised quite the debate in the industry. I can't seem to find it anymore online, but the report is called "From Dust to Dust" and discussed here. This report refutes it pretty well pointing out some erroneous assumptions, however.
posted by goodnight moon at 11:04 AM on August 10, 2012

You can debate this all over the place from a bunch of angles, as others are pointing out. One of the key phrases you'll want to use in search for support of your argument is "embodied engery".
posted by LionIndex at 11:36 AM on August 10, 2012

Also keep in mind the batteries in a prius can be recycled. Also a prius gets DOUBE the mpg as a subaru outlook.

PLUS older subaru outlooks are known for blowing head gaskets. So that car COULD end up in a landfill faster also.

In certain states the prius also can be used in an hov lane with a single rider which will also save gas and emissions.

I still think a prius is better for the environment.
posted by majortom1981 at 11:38 AM on August 10, 2012

I have a friend who does this sort of environmental analysis and he says a very broad rule of thumb is once a car has been on the road 10-15 years, improvements in technology start making a new car greener. Any individual purchase, a slightly used car will be greener than new, but over a large fleet of cars, new ones have to enter eventually. If you've driven your car for 10 years and intend to drive your next one as long, you can probably buy new reasonably guilt free.
posted by Eyebrows McGee at 11:48 AM on August 10, 2012

(I mean, the environmental load of a 15 year old car becomes so great that the environmental cost of creating a new car is less than that.)
posted by Eyebrows McGee at 11:49 AM on August 10, 2012

(I mean, the environmental load of a 15 year old car becomes so great that the environmental cost of creating a new car is less than that.)

Yeah, this is actually pretty plausible, if for no other reason that by the time you get a car that old you might have replaced up to half of it anyway.

If it's a choice between a brand new and a slightly used car, the used is better, but again, if you drive your cars into the ground, the overall difference is pretty minimal.

Really, the analysis about which car is better for the environment is pretty trivial. It's like Congress yelling about some bastard politician's $5 million pork project--which is bad!--while ignoring the $1.6 trillion annual budget deficit. Cutting 100% of the pork out of the federal budget wouldn't even begin to put a dent in our fiscal problems.

The difference between a Prius or Outback and no car at all aren't quite that dramatic, but it's the same idea. You want to make an automotive choice that's good for the environment? Drive less. Any other choice is just futzing with the margins.
posted by valkyryn at 12:12 PM on August 10, 2012 [4 favorites]

Another variable: how many miles will your friend drive in a year?

How many miles will you have to put on a used Subaru Outback for its environmental impact to exceed that of the Prius?
posted by twblalock at 12:32 PM on August 10, 2012 [1 favorite]

Consider this: If there is a market for used cars, people (like you) willing to buy them, then it makes it easier for someone who has a car that's only a year or two old to trade it in to buy a new one.

If no one was willing to buy used cars, then there would be no trade-in value, and that guy would have to spend a lot more to replace it. Thus he would be more inclined to keep it, and drive it for a lot more years.
posted by Chocolate Pickle at 12:42 PM on August 10, 2012

Well, still greener would be buying a bicycle. Or hey, yet even greener would be not having kids. The absolute greenest solution possible for any human is probably suicide, but I hope you agree that's ridiculous, no matter how rationally true it might be. This is a variation of the No True Scotsman fallacy (where one constantly redefines the terms), I would almost say, except that sounds too negative. There is no one green-EST alternative that can satisfy all use cases. I think it's most important that individuals begin to make the small changes that are appropriate for their situation: move to a walkable neighborhood, commute via transit or bike, eat less meat, plant a tree. I don't think there's anything to be gained by hounding someone into regretting their small choices as insufficient, because in the larger macro sense, as noted, just being a living human is pretty much bad for the environment.

To return to the market discussion, no, this isn't a purchase that happens in a vacuum. With cars even more than homes, you're buying a depreciating asset with a limited lifetime -- even the best-maintained car is really lucky to get 200,000 miles. You can do that by buying a used 100,000 mile car and driving it another 100,000 miles, or you can do that by buying a new car and driving it 200,000 miles. Even the person who leases a new car every two years (someone I know used to do this, don't know if they still do) is not necessarily adding to the carbon load of the earth because those leased cars are likely to get used heavily and turned over to the private sale market in the end.
posted by dhartung at 1:16 PM on August 10, 2012 [2 favorites]

In considering the questions, it is useful to remember that Toyota had motivations beyond fuel efficiency and carbon emissions when developing their hybrid system. One of the goals was to cut emissions of NOx, hydrocarbons and carbon monoxide, which play a major role in smog.

As for the Prius's battery: The warranty may be 8 years, but the car has been on the market in the US for 12 years, and even longer in Japan. There are a lot on their original battery packs. Further, the cost of replacing the battery pack 1) has declined and may continue to do so, 2) is less than an engine rebuild would be, so the idea that Prius's are going to end up scrapped when their battery gives out is dubious.

Finally, besides the battery, the Prius uses more aluminum than most cars. As I recall, aluminum requires more energy to refine than Iron, and so that probably contributes some to the environmental load of building a Prius. But that is mitigated by a few things. First, much of the energy that goes into refining aluminum is hydro power, which, while it has its own environmental costs, is probably better over all than the coal used in refining iron. Second, the aluminum, and most of the other metal in the car, is going to end up being recycled.
posted by Good Brain at 2:00 PM on August 10, 2012

Something else? After 100,000 miles, the Subaru, at about 25 mpg, will have consumed something like $14,000 in gas. The Prius--mine gets 45.5 mpg on average--will have consumed only $7,700. Even if you have to replace the batteries, you're still ahead like $4,000 (assuming equal purchase price).
posted by valkyryn at 4:48 PM on August 10, 2012

Assuming it takes ten years to put 100,000 miles on either car, you have:

$4000/10 = $400 per year, or $33 per month, to be able to drive an Outback rather than a Prius. The Outback handles like a car, and the Prius handles like a very large golf cart that is drunk. At a premium of $33 per month, the Outback is a no-brainer.
posted by twblalock at 5:16 PM on August 10, 2012

It's kind of a silly comparison because a new Prius becomes a used car and carries on being fuel efficient through its life, possibly with future owners. The cool thing with hybrids is that they recover energy when braking that other cars just use to heat the air around their brakes. That's an intrinsic advantage throughout the car's life. It sounds like you are trying to ruin your friend's enjoyment of his car - do you have a purpose behind this?
posted by w0mbat at 5:24 PM on August 10, 2012 [1 favorite]

It doesn't even make any sense, because he is already driving a used car now, and was from the day he drove it off the lot. If he took it back to the dealer and bought a used Subaru, how would that help the planet?
posted by Sidhedevil at 8:27 PM on August 10, 2012

What evidence is there that him buying a used car would prevent a new one from being made? These things aren't built on-demand. There is an inventory of already-made vehicles that is there regardless of whether your friend chooses to buy one or not.
posted by Bonky Moon at 11:29 PM on August 10, 2012