Hello 1exotic, and welcome to the cameralabs forums!
If you want to photograph still cars and have it in sharp focus but a blurred background, use Aperture Priority or Av this allows you to set the aperture (such as f/5.6) and the camera will adjust the shutter speed. For fast moving cars use Shutter priority or Tv this lets you adjust shutter speed (faster to freeze action, slow to get creative blur) and the camera will adjust aperture, use manual if you want to get real creative.
Also another tip use a method called panning which is kind of tricky, but if done correctly it can give great results, first steady yourself and as the cars is zipping by, use a slow speed such as 1/30 and follow the same horizontal fluid motion as the car. The result should be a sharp car but the background is motion blurred (this can also be done in photoshop).
As for the equipment, I recommend the decent Canon 50mm f/1.8 for really sharp still shots. Also I'd go for a IS lens (image stabilizer) lens such as the 17-85mm USM and the lens will stabilize the vertical axis (so if your hand moves up and down it will correct that). If the cars are in really bright sunlight where it would be overexposed with a slow shutter speed and Neutral density or Polarizer filter will do wonders.
I hope this helps and if you ever need more help just say so.
PS Gordon's excellent reveiw of the 17-85 is right here:
Assistant News Photojournalist
Nikon and Canon Systems
A variety of f/2.8 lenses from 10.5 to 400mm