The price of racing.
I agree with most here on different variables. I would like to add one. SPONSORS!!!!! Local business or even just an individual may what to see their name on the side of your car or being announce over the loudspeaker during runs. Instead of an individual race, it could be a group event. Could also bring out more spectators, as I see fewer and fewer showing up. Bring back the fun!!!! and make it affordable.