Actually, the Smart roadster is a neat looking little car. The Smart for Two is somewhat short on styling IMHO.
To answer your question directly, I quote MSNBC
http://www.msnbc.msn.com/id/5217861/
"So what about heading north and bringing a diesel-powered smart back over the border? JoAnne Caza, a Mercedes-Benz spokesperson in Canada, says don't even think about it. "It is not possible since the Canadian car is not certified for sale in the USA," she says."
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2003 Almond GT AutoStick, body colored rear splash guards and hood struts, chrome gear shift, AC & vent knobs, billet steering wheel spokes and pedals, AMX1397 Turbo-Intake Pipe.