Here are some sites that you might find useful about importing cars to the US:
http://www.customs.ustreas.gov/imp-exp2/informal/car.htm
http://www.epa.gov/otaq/imports/imptop.htm
http://www.nhtsa.dot.gov/cars/rules/import/
Keep in mind that Euro spec Mercedes and American Spec Benzes don’t have the same retail value…Euro spec have lower retail value—or so I’ve heard. But look at the bright side…you don’t have to worry about putting in those euro lights, would you?!