Good Topic. We experienced that same problem. Race car sitting in auto repair shop. Customers bring their cars in & ask all kinds of questions about what do those tires cost, how much is the engine in that car. Then come to pickup their car & what did they buy for the race car when they look at the amount of their bill.
Also, can't count the number of times we missed racing on a Fri night because we stayed later than usual to finish either a customer's car or radiator repair. Sat's were the same, getting to the track late because we had to get a radiator done for customer to pickup. Cars pulling in Sat afternoon leaking antifreeze & need their car fixed so they can get somewhere. That's why we're just spectators now.