Live in Florida & always run non-ethanol fuel in my 5.7 GMC Savana since non-eth fuel is readily available here and I get better MPG with non-eth fuel. On a recent trip to NC & TN mountains, I was unable to find non-eth fuel on the trip north so I was force to buy 93 with ethanol, and wondering whether I was buying 10 or 15%,,,,,,or maybe more ethanol.
During the first few days of driving up long hills, I found I was unable to maintain 50mph on some steep uphill climbs pulling my 6,000# TT. Figured it was just too much for that little engine. However, on our second week while un-hitched, we found a gas station near the Head of the Dragon in TN that sold 100% gas,,,,,93 non-eth fuel. I filled up and did not notice any difference when not towing the TT. The next day, we hooked up the TT and took off to the west. When climbing several long grades, I noticed I was now able to maintain 55mph or more where previously I fell below 50mph. Looked up BTU/Gal here: