I don't think that $4/gallon gas, painful though it may be, is enough to truly force the production ultra-efficient cars.

"Greener" might be a better tag for the current generation of cars. Greener than the 90's generation of cars, for example.

Battery power hasn't advanced a whole heckuva lot in the past generation - we're still using the same AA, AAA, C batteries from the 70's, but computer technology has learned how to become lean and mean in order to squeeze the most life out of that limited resource. So too will cars... someday.