Every one seems to have missed the real point here. Americans need bigger cars and bigger engines because we drive around on such an enormous land mass. Britian is tiny.
If I were to somehow transport my 1972 Monte Carlo to the isle, I'm sure that slamming the accelerator to the floor would plunge me into the ocean almost before I could apply the brakes. In the states, I need that kind of power and speed to propel me to work in as short a period of time as possible.
I rely on my 7.9 liter V8 to jockey for position between street lights and to merge onto Las Vegas highways. It's a war over here, and if you ain't got the displacement then you're road kill.
British cars are cute though, and I'm sure they have their uses. I wouldn't mind having one. I could keep it in my trunk (boot) and use it drive from my parking space to my office.