AF to AI servo
Single focus point
Shoot TV starting about 1/500th aiming to drop this to 1/250th or lower as you 'get your eye in' (This means that the wheels will still show movement, while the car remains sharp)
Adjust ISO to balance exposure, or use auto ISO
The specific settings in the autofocus menu are probable best left alone until you have had time to understand what they do, the defaults are still more than adequate for rallycross