Use your race to experiment, but a good starting point is shutter priority if your goal is to control motion: use a faster shutter to freeze cars, or a slower one if you want some motion blur. Your 55-200mm f/4-5.6 is relatively slow for night sports, so be prepared to raise ISO and accept that fully freezing action may be difficult under track lights.

A few practical tips matter as much as settings:

• Shoot in the better-lit parts of the track and where the light falls in your favor.
• Corners can be easier than cars blasting straight past you.
• If you know where you want the shot, pre-focus on that section of track and wait for the car to enter the frame. This helps avoid autofocus hunting.
• The safety fence can interfere with autofocus, so manual focus or focus lock may help.
• Try different combinations of shutter speed, aperture, and ISO during the long event to see what your camera/lens can handle.

Also, from the stands, 200mm may not feel very long on a large track, and a faster/longer rented lens would make night shooting easier if that’s an option.