[MTBikerTim]

The other factor is cost to the environment of the cars production. I had a teacher once who said he would never buy a new car no matter how efficient it was as the cost (environmentally) to produce would always out way the benefits of any efficiency gains to the environment.

I thought this was a very good point. I always wonder about those energy saver light bulbs, sure they save energy but how much more energy do they take to produce being so much more complex.