It's cheap race gas at about 105 octane. I had my previous car tuned for it. The only problem is that it is very inconsistent at the pump. You don't always get e85. Some times it's e80 other times it's e75. The blend is also dependent on the weather. In cold weather states you only get about 3 months of true e85, in the winter the pump has a blend of e60. For a regular commuter car it's not a big deal and is necessary to ensure it starts properly in cold weather but when talking about cars that need a specific stoich ratio it's critical. Best way around it is to buy a barrel of it lol.