realistically speaking...the brands of fuel (whether BP, Caltex or Shell) and classes of fuel (92, 95, 98, ethanol) do not contribute that much to performance (power) and efficiency (fuel consumption ratios). Yes, slight changes in performance and/or efficiency are possible, but they are far beyond the magnitude to make some "real differences", such as making the rolla like a V8 or consuming below 7L/100km. Rolla's enginer are only 4 cylinders after all... However, one significant difference that the brands and type of fuel can make is the protection of your engine. 98 petrols (such as V-power and Ultima) release exhausts that are 30~50 times LESS carbon than 92, and 20~35 times LESS carbon than 95. That will mean a far less level of carbon residue to your piston and other moving parts of the engine In a simple laboratory experiment we have conducted, feeding 92, 95 and 98 petrols to a simple Villiers Engine (the foundamental engine that all car engines bulid on) and let the engine run for 6 hours at 2000rpm. At the end of 6 hours: * 92 petrol: wears and scratches are eye-visible on most moving parts * 95 petrol: wears and scratches are microscopic on some moving parts * 98 petrol: same as 95, but the severity of damages is less Usually performance and efficiency are trade-offs, it is very hard to get both with current technology. If you prefer performance more than efficiency... then there are many options such as CAI, bore-up or even turbo charges If you prefer efficiency more than performance... then...probably drive slower is the only option...@.@ So yeah...hope this can help you...