They make rules and regulations for people to race with in the limits. F-1 is so competitive teams have to go to the maximum allowance to get that 1/10 of a second.
When I race gokart here, we check the gasoline after the race to make sure nobody mix something illegal in it. I know some racer did mix alcohol in the gas but they mix just enough not to be illegal. That is extreme in club racing but normal in serious racing.
Cheating is not a cheating until you get caugth.
