I think this bill is a joke:

Congress sends bill raising fuel efficiency standards to Bush

Bush is expected to sign the bill.

Why is this bill a joke?  Because of this:

"The centerpiece of the bill remained the requirement for automakers to increase their industrywide vehicle fuel efficiency by 40 percent to an industry average of 35 mpg by 2020, compared with today's 25 mpg when including passenger cars, SUVs and small trucks."

If we're still relying on fossil fuels such that we only need an efficiency of 35 mpg in 2020, then the innovators and entrepreneurs of the world must be asleep today.  In twelve years, I would hope that no new car is manufactured to run on fossil fuels. 

I suppose that you have to take small steps first.  You have to start somewhere.  But a 10 mpg increase just doesn't sound like much of an incentive for auto manufacturers.  Can't they already manufacture cars at that level of efficiency?