The E85 pump at the gas stations in NorCal is a seperate company and not affiliated or owned by that gas station. So, they obviously have a deal between them. We don't have many pumps and I've only found 2 companies that produce/offer it.
Propel Fuels which markets their E85 as high performance E85. Whenever I test theirs, it always test at E86-E87. If you're lucky enough to find a Propel pump in your area, definitely make it your go to pump. I always try to bring several jugs whenever I fill up.
The other is Pearson Fuels. A new pump opened that was actually near me, so I was hoping it would be just as good as the Propel. It wasn't, it was just ok, I guess? It tested at E80. But what got me worried, was the sign on their pump that said it could range from(I can't remember) either E51 or E57 to E85. With a wide, potential variation like that, I definitely won't be stopping at any of their pumps again. Way too risky.
So, beware where ever you're buying your E85 from. There's a good chance you're not getting what you think you're paying for. Even though the Propel has always tested a smidgen above E85, I always test it everytime. For the cost of a E85 tester vs the cost of an engine repair, there's no excuse for not erring on the side of caution. All it takes is one bad batch or an improperly sealed tank to leave your car in a busted up condition. Don't be a dummy.
For a E85 tester, I like and have been using the Rev X E85 tester. I got mine off of ebay.