Where it's better and with which gas (esso/shell/couche-tard,...) (87 octane/91, ...)
it's weird!!!!...for me, with the Esso 87 oct, I noticed a VERY dramatic mileage decrease! lol...don't know why but in city, I did 175km with a half of my tank.In my experience, they are almost all the same. However, once I experienced a VERY dramatic mileage increase using Esso 89oct. A difference of almost 150KM on a single tank(all highway)
I think that shell have the "V-Power" ...nitrogen?I get the best mileage from Shell 89. I think it's because it's the best mix of ethanol and Octane.
I get an extra 50km-70km per tank.
Pretty much all gas stations' in Ontario 87 octane (regular) contain ~10% of ethanol.
Shell 89 contains 5% and 91 contains 0. Strangely 91 doesn't help. I think 89 Octane allows for our relatively higher compression engine to allow advance the timing a bit more than on 87.