I run my E86 N52 on E10, E5 and left over race fuel depending on where I am and how poor I'm feeling ! The race fuel is usually Shell V-power with a dose of Torco unleaded fuel accelerator (250ml/20l) which adds about 4 octane points. I buy new for each race meeting and the Z is the only other car we have that can use it. I can't say I have ever noticed much difference between any of them although I probably don't do enough mileage for all the adaptions to work through fully. I don't keep consumption records other than the dash readout so don't know if there is any difference there.