I just thought I'd give the premium a try to see if I got better mpg without the 10% ethanol because just an extra 20 miles would have paid for the difference. Didn't work. I just filled up and got 20.6 mpg which was just about the same as 3 weeks ago when it was regular gas.

I have only ever gotten 36 mpg after filling up after a road trip. I live in Wisconsin so I won't be using my a/c for months.

 

no CELs or anything? something is seriously wrong with your car id guess.

 

Yes, something is wrong. I only hope it is not serious or too serious.

 

Assuming you've already checked the obvious, air filter, fuel filter & pressure, and none of the brakes are dragging, pull the plugs and give them a visual inspection. They're great problem indicators. Keep note on what cylinder each plug came out of.

Here's a pic of common conditions:

 

Edit wrong thread.

 

Turns out it was the plugs. It was not too long ago that I had my first tune-up and I took it to the Ford dealer where I had my synthetic oil changes done. Evidently they simply put in Motorcraft copper-top plugs, and couldn't be bothered to check what plugs were called for by Toyota. Had them replaced (by someone else) and my mileage went from 20 mpg around town to 30 mpg.

It was simple after all.