BRZ is getting better gas mileage with OFT e85 tune?
 

Did my first tank of e85. I follow the first time using e85 instructions.

Now my car is showing 30mpg on e85 vs 29mpg on 91.

Car is full bolt on.

any idea whats going on?

That is because your sensor isn't accurately reading the fuel consumption. E85 uses about 25% more fuel than regular pump gas. Your sensor for mileage will be off by 3-5mpg roughly. You were probably around 25-26mpg on E85

To get the ecu to run e85 the injector scalars are bumped up 33% , but the ecu does not take this into account when calculating fuel consumption figure shown in dash.

If you want to read correct fuel consumption on e85 oft tune you will need to modify the "fuel display multiplier offset" table in the tune to bump up values by 33% their as well, see tune tweaks link below