OFT Stage 2+ E85 better MPG than 91 octane
 

Been running OFT Stage 2+ v4.03 (on 91 octane) for six months averaging 23-24 MPG. Swapped over to Stage 2+ E85 v4.03 about a month ago (running E85 octane obviously) and noticed my MPG increase to 27-29 MPG. No new mods or changes to the tune. Didn't change how I drive. I'm just curious if anyone else has encountered the same change. I was always under the impression I'd lose around 30% MPG on E85 vs 91 octane.

Car:
2017 Subaru BRZ 2017 Performance Package

ECU:
OFT Stage 2+ E85 v4.03

Intake:
K&N Cold Air Intake Kit

Exhaust:
Tomei Expreme UEL Header
Tomei Expreme Over Pipe
Magnaflow 15157 Cat Back Exhaust

Tires:
Michelin Pilot Sport All Season 4 - 215/45ZR17

Check mileage between fill ups. Dont look at the dash display

Something wrong

Yes, it is literally impossible for you to get the same or better gas mileage if running the car the same as you always have. The dash does not display the correct gas mileage, you have to do your own calculation based on your fill-ups. With a proper tune, there is some improvement in efficiency, so to a certain extent you may have "improved" gas mileage, but with E85 it will definitely be quite a bit lower.

91 I was averaging 28-30 mpg
E85 averaging 22-23 mpg

The loss in mpg is just slightly more costly than the savings of the cheaper fuel in my area. Wow that sentence hurt my head.

Worth it, but I have no idea how you're making more mpg

OFT V4 flash on E85 and doing 18-20mpg

Me too. No way to get better gas mileage on e85.

If the calculations for mileage aren't changed it won't read correctly. I don't know how you were getting only 22-23 on 91 as I would get 36 for long highway trips and 28-29 when averaging locally.

On E52 (best I can find in Arizona) I now drive almost exclusively city and I get like 17-18

Jaden