There's a gas station about 4 mi. from the track that sells 100 octane race gas for 5.99/gal. if you don't want to pay 7.50 at the track. Rt 985 and Rt 53. I think the station is Kangaroo.
Exit 16 off 985. It's at the intersection (south side) as you're headed toward Road Atlanta. Race gas pump is next to diesel pump. You'll need to go into the store to tell the clerk to turn it on as it's old technology.