The stations where i fill up in my college town are all 91 octane, no 93, and I usually fill up with v-power. I noticed on the sign near the phillips 66 station, it was advertising "no ethanol in our gas." I thought i'd try a tank out since it was the same price as shell and see if I get better mileage.

So what's better, top tier gas with ethanol, or a lesser known station gas with no ethanol added?

 

I'd vote the Top Tier fuel myself. Shell makes good stuff and I've used V-Power before. If I have a choice though I usually go for BP or Mobil gas stations. I've never had a bad tank from those two before. The ethanol itself is not going to hurt your car any. In fact, it may even prevent detonation if you're borderline knocking.

If you want to prove it to yourself, get a datalogger (or borrow one) and run your Tank to E. Put about 5-10 gallons of one gas in the tank and watch the knock sensor. Then after it's on E again do the same with the other gas station. Whichever gas you start knocking with or (I hope this isn't the case) have more knock with is the lesser in this instance.

 

i would go with v power, the ethanol and the top tier detergents will keep your fuel-injection system clean. you will technically get better mileage out of a tank of gas without ethanol because a car must burn more ethanol to create the same energy as pure gasoline.. very small difference though,like 2% worse mileage over pure gasoline.

 

What he said. Thermodynamically speaking, ethanol isn't as good as gasoline.

 

Get 91 and use octane booster or meth.

 

wasn't asking anything about this at all.