But going from, say, 20 mpg to 25 or 30 mpg would still be a significant improvement at the current gas prices.

In any case, I think the next generation of cars, and to a lesser extent, trucks, are going to be more aerodynamic than the current generation.

And US car companies are hammered partly because they didn't have the foresight to start developing hybrids in time. OK, the Honda Insight was a flop (albeit if it were on the market, it would probably be selling like hotcakes right now ), but the Prius was a runaway success. Because of their weight and RWD, trucks and SUVs would be ideal for a hybrid option: it should be relatively easy to add 2 small electric motors to the front wheels that can do regenerative braking, propel the vehicle at low speed, make it to a 4WD, or help during heavy acceleration.