That’s a very good point. That is quite true. Though probably unlikely. By putting your money into the used car market, you are effectively raising overall demand for used cars, putting more money in that system, so unlikely for someone in this market to switch to something cheaper (like a bus), more likely they will switch to something more expensive, like a new car. But a fair point.

If the goal is to save my money and reduce my carbon footprint, it works… in the short term.

If the goal is for me to be a consumer with a conscious for the broader market, I should probably purchase a new fuel efficient car and suggest all my acquaintances do the same.

One person’s carbon consumption is negligible, just like one person’s vote or political influence, but when the market changes preferences you see large effects. (Obama? Change?)

Micah: a ’98 Tercel might not be fuel friendly at all, but its production has already been accounted for. You’re right that it probably won’t last 130,000 miles, but might trading it in for a ’99 Tercel (and probably a ’00 Tercel later) still be more beneficial than switching to a Hybrid?

Having said that, it’s an interesting point that new cars might end up being less fuel friendly as a consequence. Yet another factor for the ever-complicating equation.

Fuel friendly used cars only exist become someone previously purchased a fuel-friendly new car.

There are probably some other valid considerations, like the demographic differences between new and used car purchasers.

It’s worth noting (again) that the used car market consists of the surviving new cars from a previous period. A more efficient mechanism to increase the fuel economy of all cars may be to increase the consumption of economically friendly new cars.

Say, for instance, that fuel conscious buyers heed the advice above and only purchase used cars. New cars will be left to be purchased by the less fuel conscious consumers. Market demand for new cars will drift away from the fuel friendly and the market for used cars will likewise follow.

I think that for the fuel conscious consumer to purchase a used car instead of a new hybrid, that consumer may be inadvertently pushing the market in the direction opposite their intention.

But to clarify, it is important to acknowledge that by switching from a new car to a used car, you essentially force somebody out there to switch from a used car to a new car.

Let’s say there are 1,000,000 used cars out there with 1,000,000 used car drivers. If you buy one of them, you deprive somebody else of their car. If you buy one of them, there are now only 999,999 used cars for 1,000,000 drivers. So you have forced one of them to buy a new car.

That is the first order effect. There is a 2nd order effect if you cause used cars to get utilized more. But the size of that effect is ambiguous and probably small.

Which means, I think yours (and Wired’s) calculation don’t make sense. Buying a used Tercel still induces some other new car to be produced, and you have to account for that.