Agreed, I have always said that no passenger car in America really needs anything larger than a 1600cc engine. In school, I used to have a little 1600cc Carolla that would hit 70 with four people in it -- good enough for any speed limit in the country.
It we, as a nation, were
really serious about energy conservation, Congresss would come up with a plan that would permit low tax "basic" personnel transportation and then an agressively escalated tax on excess HP, or perhaps displacement. Until that time they (we) are simply not committed to it.
Doing this would be fair. It's the American way -- you can have it if you want it, but you will have to pay through the nose.