I saw a Chevy Volt on the road yesterday, no plates of any kind, though I believe they are being sold already.
We get to see the new prototype cars on the roads about a year before anyone else sees them. They're easy to spot. They're either covered 80% with car-bra-like material, or they have this psychadelic white/black op-art paint. This paint scheme is meant to camouflage the car so no one can pick up the styling detail, but all it does is draw my attention.
Back in the early 80s I remember seeing the Dodge Daytona two years before it was introduced. It was a clay model in the Chrysler studio. It really got me excited because car styling was rather boring at the time. The hottest cars from Detroit at the time (except for Corvette) were the Ford Fairmont, Mustang, and I think the Chevy Celebrity.