Yeah what I've commonly been able to find at tracks around here for higher-end unleaded fuel is Sunoco 260-GTX (which is 103 RON, or 98 using the normal average we see on commercial gas pumps in the US). I usually put a few gallons in once during the weekend just because whatever (too lazy to drive to the gas station and/or hoping it helps clean the system or offset some heat).
Once or twice I've filled up on the stuff, but it just costs too much and I can't really tell the difference on-track definitively. How tired/focused I am, how my tire/suspension setup is doing, and whether I've really got my lines down or not all have like 1000% more impact on my lap times than whether I'm running the best gas or not, at this stage
