Ok a mclaren f1 (i spelled it wrong before it is mclaren) is a superduper exotic sports car that cost like 1 million usd a piece and are put together by hand and they are illegal to drive on public roads in the .U.S because they are wider than american standards. The us says cars can't be over a certain width and the f1 is wider than that. You can own one, you just can't drive it on public roads.
a smart car is a little teeny inexpensive car that is very small. You know how small a geo metro is? A smart car is even smaller. I think they are optimized for parallel parking! Well they are very popular in paris because all the parking is parallel parking, because the city was built before cars and you can only park on the side of the road.