There's all kinds of sensors and such in modern race cars, use the basic G-loads to send to a full hydraulic simulator with VR helmets. For $50-$100 fans can get in, strap in, and experience the entire race like like Hamilton or Dixon or Truex. Medical waiver required.
Choice two might be more realistic - feed all cars in a race to a sim, drivers at home can compete in the the same races real time. Obviously, you couldn't affect the "real" cars you're racing against, but it would be a blast anyway.