Originally Posted by
raff
Unless you have a series 2 or use a x-cal type arrangement- tuning for E85 would obviously restrict you to E85 which in Melbourne is few and far between which would be a real pain in the arse. I have a series 2 and find the cost vs milage is in favour of 98 octane regular fuel. Seat of the pants performance I cant notice much power wise between the two. I occasionally can notice a momentary ping under load, high gear, low speed- both running BP98 and E85, fuel octane hasn't made a difference.
if your worried about regular pinging the answer should be in the tune, not upping the fuel octane- the tune should suit the fuel at time of tune, not the other way round! Speak to the guys at Autotechnique and ask their advice