[Big Dave]

Back in the 70s, the product now called E10 was called gasohol. People came to loathe the stuff.

Your MPG is down because gasohol has a lower heating value than straight gasoline. Heat is what turns the wheels, Lower heating value means you need more fuel to go the same distance.

The alcohol in gasohol is hygroscopic. It readily combines with water (ask your bartender) and when it does it comes out of solution in the gasoline. It is so hygroscopic it will suck water vapor out of the air. When some of the vodka (water/denatured alcohol mix) hits the filter it clogs it.

Apparently, we are doomed to make the same blunders (in this case gasohol) every thirty years or so.