Hi there,
I just stumbled across this thread as it's been bumped up!
Heidi - your first point of call will be these guys
http://www.gnkauto.com/facilities.htmlThey do conversions for cars built outside the UK to be US road legal. They do have a Smart car program as well. I spoke to these guys some time back about certain cars and to just get some general information.
There is some slight incorrect information in the threads so far. The 25 years old rule is for cars that are right hand drive only. If you want to bring into the US a left hand drive car, then that age limit doesn't apply. Pmorita's car is 30 years old, so perhaps with some mechanical work and federalising etc will be able to 'relatively' easily, begin to enjoy the car in the US.
You'd also have to cover insurance, any US import taxes and duties on the car once it arrives in the US as well. Those charges will probably wipe out a majority of the savings of buying the car here in the UK.
No point in getting a MINI over in the USA either, it's already officially available there. Smart cars are also officially available as well.
The realistic reason to import a car into the US, is for special, high performance, 'relatively' high value and interesting cars only. And from what I've read of some of the guys who've brought in E34 BMW M5s, Porsche 911 GT2's etc is that it's quite expensive, and the M5 for instance would be at a purchase price of only about £500-8000. Add on perhaps £4-5000 for all the shipping taxes, customs, federalising and testing costs and that'd be a good indicator of the kinds of costs you'd be looking at for a personal import Smart Car.
Cheers, DtM! West London & Slough UK!