Not OP, but I do (a fair amount of) HPDE/TT with an m240i, converted to the cup car spec.
Running costs for me are ~$500 / 2-hour day on 100-TW tires. These cars aren't exactly light, so they eat through consumables. Tires are the largest part, then repairs, then brakes. This doesn't count fuel.
If I had to guess for OP in PWC, 50-100% more, mostly driven by slick costs.
Running costs for me are ~$500 / 2-hour day on 100-TW tires. These cars aren't exactly light, so they eat through consumables. Tires are the largest part, then repairs, then brakes. This doesn't count fuel.
If I had to guess for OP in PWC, 50-100% more, mostly driven by slick costs.
EDIT: added fuel note