Being an anal
engineer I track all of our costs and we spend anyware from $95-$150 on a given night (assuming no wrecks) this includes gas money to get to and from the track, gas for the racecar and pit access for me and my wife. The biggest cost for me is getting to the track (most of my tracks are 1.5-2.5 hours away). Most pit passes are in the $25-$30 range per person. The car doesn't use much gas. Plus my wife makes us sandwiches and packs snacks so we don't have to buy track food.
I also keep track of my amortized costs for things such as depreciation on my trailer, to vehicle, racecar chassis and engine. This amounts to about another $100 or so per race. But these aren't realized costs until you need to replace the item.
Gerad
