Does anyone have any specific & detailed knowledge of how to do this? I read that taking the vehicle apart, bringing it to US in separate shipments, assembling it, and registering it as a kit car is one way of doing it. I know there are one year exemptions for cars, but that's no good. What about bringing the vehicle here for racing purposes, clearing it, and then registering it as a kit car? There have got to be overlapping laws which create loopholes.
http://www.epa.gov/otaq/imports/quiktext.htm
The One year exemptions depends on the person, you'd have to have been military stationed where you could have bought the car, or in the US living here temporary (i.e. under a visa).
The Epa is the least of your issue's. It's the NHTSA thats your problem. They require crash testing and then modification. EPA shouldn't be huge issue, atleast if you purchase a model with an engine sold in another BMW already available in the US.
Even if the car is easily able to pass crash standards you will still have to modify things like the lights. An Example is the E36 light covers, in europe they are glass, in the US those are illegal. Technically many of the bulbs and entire light systems are illegal (don't have DOT approval). Hell on the Audi RS4, those massive seats that Audi claims keeps the drivers head protected, are illegal in the US, and Audi has to change them out for sale here.
The only people who import cars like this are usually those with plenty of cash, and who want exotics not normally sold here, or there's a waiting list for. I doubt there are many people on this forum who are in that situation.
If the car is truely destined for the US in a year or 2, I'd just wait it out. It'll take that long to get the car otherwise. Customs puts several mandatory holds that last several months on the cars.