OP thanks for asking the question. A gas station near me (Brentwood) sells 100 octaine and I always wondered if I should try it or not. Looks like NOT.

 

I would love to be able to buy 100 octane when traveling with my Tridents, which require high octane. I've stopped at airports and bought aviation fuel, which is illegal to do, but many small town airports have credit card pumps.

There's a station just south of Deadwood that sells racing fuel during Sturgis week.