Petscar

Just got 23.5 mpg. Normal is about 19.5. Since putting her back on the road, I have only been using 91 octane 10% E. Switched back to no ethanol 88.5 octane and got the 23.5 mpg. And as I have said in the past, she runs so much better. Smoother and more pep. Others have indicated they have seen no difference using no ethanol, but for me, that is not the case. I guess my baby just doesn't like ethanol.

mazdaverx7

iTrader: (6)

Wow that's really good!!! When I had a new 05 6spd, I was getting 22mpg consistently and thought that was pretty decent. 23.5 is really impressive as I am currently getting 17mpg with my 04 6spd.

CaymanRotary

I got about the same. Around 15-17 mpg on my 6 speed. No highway driving only city. I suspect if you are on a highway most of the time you would see 20+ mpg.

UnknownJinX

I never noticed anything between running Shell 91(E0) and Petro-Canada 91(E10). Realistically I don't expect much difference between the two unless you leave the E10 sitting for a very long time, in which case it's bad for the car.

IIRC you live at a high altitude, right? In which case 89 should be sufficient.

I never saw past 20 MPG myself but I have a lead foot and I rarely do purely highway trips.

Petscar

The altitude is about 6000 ft and I do take mountain roads occasionally at 10,000 ft.

Petscar

I have a lead foot also but recently I've been driving a little more docile.

TeamRX8

iTrader: (25)

it probably just means compression is low, because higher octane is proven on the dyno with a fresh, full compression engine. Or at least when operating under full power, not that anybody’s butt dyno ever lied to them.

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Petscar

I am pretty sure I read on the forum as compression goes down gas mileage diminishes. My gas mileage is improving.

mazdaverx7

iTrader: (6)

The compression in my 04 is on the lower end of the spectrum. I have newer ignition components with BHR coils. This helps the engine remain running and not showing signs of deterioration. The low mileage I'm seeing is likely because of the lower compression. I'm aware of it but I just roll with it.

Petscar

How many miles on the 8? When you say lower end of spectrum, in the passing or failing zone? Have you tried no ethanol or reduced octane? I'd be interested to hear if you saw any difference.