I can only wonder what the hell race gas will cost these days. Back in my grassroots racing days, a barrel of 110 octane was about $1,200 CDN, and would pretty well last a weekend with a few test sessions and 3x20 minute races. I remember the last 24 hrs of Daytona we ran I signed for all the gas in one car, and it was about US $19,500 for the 24 hour race alone. I'm sure it hasn't gotten cheaper since then. Again... first world problems.
Champcar has "pump gas only" rule. I'm pretty sure everyone follows the rule, too. I feel like I could pick out a car that was running 110 by the smell, and my nose didn't detect any at Road Atlanta.