Apparently hybrid cars don’t actually get the great gas mileage the EPA ratings indicate. Angry car-owners are holding their fists up in the air to the car companies, but the car companies claim it’s a side-effect of out of date testing methods employed by the EPA. Still, you don’t hear the car companies mentioning that when you go into purchase a hybrid.
On top of this, something like half of all the energy consumed and emissions generated by a car are during its manufacturing process. Buying an old Volvo is probably better for the environment than buying a brand-new hybrid. Still, every little technology step in the right direction is worth supporting in my opinion.