How to photograph a street legal racing car?

The only thing I can think of is a very high ISO and a very very high shutter speed (when they are racing).

yeah, time of day would be helpful for some better answers, but no matter what i would say high shutter speed

I’m assuming it’s at night? People don’t usually street racing during the day.

these are street legal, so its not illegal street racing, i would assume so they could be racing on tracks

Ok, lets forget for a while about the speeding issue.
Say the images are to be of the car sitting still. What do’s and don’t should I consider?

If the car is just sitting there, and you have a DSLR, then change the ISO low. You will get a crisper image. Also, you can adjust the aperture to let in more light. Finally, the shutter speed should be slow if the car is just sitting there. Those three things will let you allow the light you are seeing to really soak into the camera to get a nice, detailed shot. If you set the shutter speed to very long, however, you might want to use a tripod. The clearest shots are ones that most people would never be able to hold the camera still enough to take- they have to be taken with a tripod.

Bear in mind that if it’s night time (or any situation where you have less light) you want to open the aperture larger and allow the light to soak longer because there’s less of it.

If you don’t feel like messing with all these settings, just take several shots in each mode on the camera: landscape, portrait, etc.

If it is while the car is moving I would recommend using a rear flash. My Nikon d40 lets me set the up in some of the more manual modes. It fires the flash right before the shutter closes. If you time it right you can take a picture of the car passby from behind so that tails of red lights come out of the car and the car looks like it is siting there. Kind of like when Superman quickly runs into the frame and stops.

Set your ISO low and open up your lens all the way. Move back from the vehicle to take your shots. This will put the background out of focus while the vehicle is in clear focus (use your depth of field preview if you have one). You may been a neutral density filter to avoid overexposures.
Or, try a Lensbaby lens for some cool special effects (http://www.lensbabies.com/). BTW, there is a lot of car photography on Jay Leno’s car fan website: http://www.jaylenosgarage.com/