You should invest in (and use) a tripod, a circular polarizer, a couple of remote flashes/strobes with lightstands. You don't have to spend a lot.
Additionally, you should read, "Understanding Exposure" by Bryan Petersen, and frequent some of the car strobist forums. See this thread - The automotive strobist setup pic thread - Canon Digital Photography Forums .
Make sure that you nail, focus, composition, and exposure. If you shoot in RAW, you can dial in WB and contrast in post.

Shooting car events is different, of course. I usually slap on my CPL onto a wide angle, use a small flash for interiors, and carry a tripod if bracketing or at night.