Another thing you can do is to go onto Flickr and look up pics of cars and look at the camera settings people on there are using (check ISO, speed and aperture (sometimes called f-stop..will be seen like f3.8, f6.0 etc on cam settings).

Also, watch where your lighting is.. make sure to keep light behind you. If there are street lights around, try to keep them out of the background as well. Don't use one light (i.e. parking under a single street light) for light up your subject.

Use the timer setting on your camera..set it to like 2 or 5 seconds, this will assure you don't get any vibrations from hitting the shutter (this really works well on lower end/mid-priced cameras...those nice DSLR cameras are much better at taking lower light pictures)

Like Chad said, use a tripod.

What kind of carea will you be using?

(oh and moving to the right section for you)