With gas prices at $7,50 a gallon, it doesn't make too much sense to have an American car in Europe. I guess that's why Detroit tries to sneak into the old continent with Chryslers rebadged as Lancias these days.
The problem is not just that our roads are narrower. European cars were simply more advanced and better built just until recently, when the Big Three finally realized that the eighties were over. So the only real reason for choosing something from across the pond was simply that you wanted to stand out from the crowd, and were willing to pay a price for that.
Still, there is a surprisingly large number of American cars on European roads. Next to the perfectly restored garage queens, supercharged muscle cars and '66 Mustang convertibles for a truly unique wedding experience, there are also some older cars which people are using as their daily rides. These are cheap as chips, and parts availability is great, so sometimes it's actually quite a good deal. Other times, you just want a Corvette. A pussy-magnet-yellow one.
My picks below, feel free to add some more.