Since I can't photograph the cars outside...

Dan,

I like the dramatic lighting on the last one.

Here's a shot I did a while ago as a demonstration of focus control. I think the shot at the top looks like small models, while the shot at the bottom might be mistaken for larger cars. Of course, the background is totally unrealistic for life-size cars (unless there is a substantial budget).

This is lit with a flash behind a sheet of diffuser. The "floor" surface is a piece of plexiglass. Both were shot at f/13 with an 85mm lens.
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Here's a shot from about a year ago (sorry for reposting my own images). The "road" surface is a sheet of foam from a camera case, the "guardrail" is a sprue of modeling plastic, and the Yosemite background is a poster. The car is less than 3" long. It was shot with a 24mm lens, to take advantage of the inherent depth of field and to get as much of the background poster in the shot. If I had shot with a longer lens (105mm for example), the background would have been much more out of focus and the angle of view would only include the bottom of Half Dome and some tree branches. It also adds some perspective to the car.
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