In December, General Motors and DaimlerChrysler showed off the technology at the heart of their recently ­announced hybrid-car partnership. The companies said that the contraption -- a transmission packaged with two electric motors -- would be in vehicles for sale in 2007, boosting their fuel economy by 25 percent. GM's announcement claimed it would "advance the state of hybrid technology in the industry." But the system will, in the end, produce an SUV that averages about 20 miles per gallon instead of 16; the Toyota Prius hybrid averages 55.

Still, experts say the new technology is a real advance. It's just not one aimed at changing the gas guzzler culture. GM and Daimler have built a hybrid system that's geared to squeezing a few extra miles per gallon from the big engines inside beefy pickup trucks, SUVs, and luxury sedans.