The RHD part will make little, if any difference. When importing a vehicle, the tough part will be emissions and safety. You will most likely have to provide evidence that the model you wish to import has been tested for and passed EPA and FMVSS requirements applicable to that year and type of vehicle. The Federal Motor Vehicle Safety Standards are codified into federal law and are available online if you look for them. They are quite involved, and some of them involve destructive (crash) testing. About the only way you are going to get a single vehicle imported is if the manufacturer has done the required testing already.

However, there are some loop holes, particularly if the vehicle is old. I wish I could provide some specifics, but I haven't tried to import a vehicle. I do know that a guy I worked with was able to import the '63 VW that he bought new in Germany, but that was in the 60's. I also heard about five years ago about a friend of a co-worker who brought an old Fiat over from Italy, so I know it can be done.

Did you have a specific car in mind, or do you just want something RHD. If it's the latter, look for something that's already here, like a Postal Jeep or something.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.