Sounds like it's not too likely to happen:
http://www.washingtonpost.com/wp-dyn...072601820.html
4% a year seems rather reasonable of an increase to ask, somewhat sticks the auto industry with going completely hybrid in the next 15-20 years,
Either that or make smaller cars again.
CAFE FAQ:
http://www.ucsusa.org/clean_vehicles...l-economy.html