No, I did not check the specific gravity of the different fuels. That would be a little bit odd to do at a filling station.

I trust the owners of the filling station. They are a mom and pop shop, and go out of their way to provide good service. It's one of the ONLY shops in town that still has full service!

I actually asked the owner about the lack of ethanol in the gas. She said "we'll keep buying until they won't let us". I believe her.

Cliffmac - I respectfully disagree with you about the triviality of octane ratings. Higher octane fuel burns slower, that's a fact. If an engine is timed for the slower burning fuel, you risk damage by giving it low octane, faster burning fuel. If it is timed for lower octane fuel, then you waste money and lose economy and power by running high octane. If your chemist pal didn't mention that, then perhaps polycyclic aromatic hydrocarbons aren't his specialty.

Johnjzjz - I think you might be on to something.... The car requires 91 octane gas. Perhaps the 93 octane PURE gas was in fact so much better than the BP stuff that my motor just couldn't burn it optimally. I just filled it up again today. If nothing changes MPG wise during my next fill up, I am gonna try a little experiment. I'm going to try 50/50 93 octane and 87. That should leave me with a 90 octane rating. Perhaps my MPG will re-appear?


-tp