Have a look at my automotive Gallery:
http://www.lightflow.co.uk/gallery_202753.html
The Bentley GT is lit with a single speedlight on a lightstand. The speedlight was wirelessly triggered with Skyports.
I placed my camera on a tripod and took multiple shots, moving the light around the car, making sure to keep a constant distance of the light from the car, so that the illuminating power is roughly the same. The images were then blended into one image using layers in photoshop.
This was made possible because the car was placed in the shade of the building and the speedlight is just powerful enough to have some effect over the ambient level (which I have controlled using manual settings on the camera). I couldn't use any modifiers to soften the light because that would cause too much loss of power.
The MG K3 Magnette has the same technique, one speedlight, but this time as it was indoors I was able to use a shoot through umbrella, because it was darker and there was only a relatively low ambient light level.
With this technique you must obvisouly ensure that your camera does not move between shots. So you need a sturdy tripod and a cable release.
You need to watch out for reflections of your light source in the paintwork and you may or may not want those. The best thing is to take lots of images from many angles and then you have lots of frames to take areas from to blend together.
With a bit of patience and precision you can get great results with a simple setup.
Ash