Just a thought - how many Americans would be prepared to pay 5 pounds/8 bucks just to drive to the center of town, as we will have to in London after Christmas ?
(That is after they they have paid US$8 a gallon for petrol)
The real way to get people out of their cars is to make a public transportation systemthat is faster, cheaper, and 'better' than the car. This is just about possible in Europe, but very difficult in the 'new' world