If we committed to gradually raising taxes on fossil fuels in a predictable way, we would encourage the purchase of more energy efficient vehicles. Even prices half of what they have in Europe would go a long way towards this. If you knew that in 10 years the minimum price per gallon would be $4-5, and that taxes would be going up ~$.25 a year until then, your next car purchase might be a smaller one than otherwise.
Opting for electric cars, while obviously a nice idea, is currently even harder for poor people than raising fuel prices. A Volt will be $30k after tax credits; a Corolla is less than half that.