To be legal in the U.S., the cars headlights would need to be a certain distance off the ground, as well as the tailights off the top of my head I think its around 22-23". Each state also has its own statutes limiting what can be road legal. In WI for example no car above 800 bhp is considered road legal. Also, tires are another thing which can exclude cars from being road legal. The depth of tread and driving semi-slicks in the winter are just a few.