Set Flash Mode to 'Automagic'
Ken Brown, who also took this awesome photo of a Mercedes 300SL using just two speedlights, has posted a YouTube video of himself shooting some spiffy cars.
He uses a single SB-24 speedlight, handheld in a softbox, and walks around each classic car popping the flash in a darkened room with the camera shutter left open.
Kinda hard to see what he is doing, because he is only visible during the flashes. But the payoff comes when he shows you the final photos. Amazing stuff this, especially for one small flash.
(UPDATE: Ken, AKA Mooosehd2, has been answering some Q's on the technique here.)
Ken, you should be teaching seminars on these techniques at big car shows...
Know of other cool, flashy videos? Link me in the comments!