Slight Thread drift
High perfromance car users used to sneak some from aircraft bowsers as there was less tax making it cheaper than specialty racing fuels that were more expensive for the same reason.
I used to drive a 1974 Toyota Celica which had a worked Twin Cam Engine. (Almost Full Race specs) Back in the late 90's Avgas 100LL was cheaper than Unleaded Fuel and the engine pinged like hell on straight Unleaded, so ran the Car solely on 100LL. Car performed very well!!
Then had to switch to Premium Unleaded (98 RON) when I could no longer source the Avgas and didn't really notice any decrease in performance.