The answer is no. They are not legal in the U.S. by federal law. Here is a great site to read more information on this topic.
http://www.minitrucktalk.com/showthread.php?t=432
and
http://www.minitrucktalk.com/showthread.php?t=188
The New Japanese Skylines are illegal in the U.S because it is still a Japanese converted spec not available for use in the U.S and therefore not street legal.
Yes, in fact it is the fastest street legal car in the US.
no
There is no limit on horsepower as long as the vehicle is street legal in every other way.
Newly built two-stroke motorcycles are not street legal in the US, nor are they likely to ever be legal again. However, two stroke motorcycles and scooters built before current regulations are still street legal. The Yamaha RD350 was the last street-legal two-stroke to be sold in the US.
No. The FXX is street legal.
If you can buy it in the us from a dealer, you can drive it in the us.
yes they are legal but you cannot race with them are at least dont get caught
no they are not street legal meaning you cant use them for transportation
Currently it is the Hennessey Venom GT at 270.49mph.
yes and No. Like Any Euro car - If bought in Europe and shipped privately, it will not Pass US emmissions just for starters. There are certain things one has to do to make a car "street legal" in the US - That includes State Inspection , Insurance , The whole schmeer. I have a Toyota supra and a Pantera that are NOT street legal - because I dont want to spend the money to bring them up to US speck. That Said, YES, Lambos can be owned legally - IF you by it here in the US through an Exotic Imports Dealer. Before the dealer can actually sell the car in the US - HE has to modify it to meet ALL US CODE.
I believe that any vehicles that are 'legal' on the roads in Canada are also considered 'legal in the US. Many of the vehicles sold and driven in the US are actually built in Canada.