I ran a tank of 100 octane race gas when a local station had it on sale for $3.879 in order to sell it off and drain their tank so they could and use it in the coming winter for Kerosene (they do this every year).
The car ran great, smoother, most likely due to the fuel being dryer (race gas doesn't absorb as much water). It was likely making a couple more ponies, but not like the Second Coming or anything.
IMHO, if it's not competitively priced with street gas, it's waste of money.
