Green Living... The fourth R: Retain

In the infamous study comparing the life cycle costs of a prius versus a HUMMER, there is a grain of truth hidden within the mis-direction: The longer you keep something, the more the cost of building it is amortised. So if you have a reasonably fuel efficient vehicle,what can you do to reduce your impact on the environment? the answer should be blindingly obvious: keep it as long as possible to avoid the cost of building a new one.

For it to be environmentally worthwhile to buy something new, the improved efficiency of the new thing has to overcome the environmental cost of building the new thing in the first place. Further, just because you get rid of a car, does not mean it is no longer in use (unless you take it to the crusher.) so looking at it macro-economically, the asking price or perceived value of gas guzzling vehicles has dropped, making them cheaper to run. Making vehicles cheaper, means more people will be able to afford them, which means more people will be able to afford to run them. Replacing a five year old GMC Jimmy with a Prius just adds the Prius to the enviromental load of the planet, because someone else will keep riding the Jimmy until it dies anyways.

It would be interesting to see a study on how these balance out. It might really be true that, ecologically speaking, for who replace their econobox every two to five years might very well be polluting the planet more than someone who keeps the same pickup for15 years, but it's hard to say. If you are buying a new vehicle anyways, then by all means find something fuel efficient, but if you have a five or ten year old vehcile, it is probably better to keep it until it is unusable, for the environment's sake.