[mart35]

I know for a fact that the same engine on a dyno running Tesco premium 98 made 1/2hp more than tesco standard 95. That was on a 613cc supermoto single kicking out 72bhp. No idea on fuel consumption on that motor as it was not a consideration. If you scale it down to a 150cc motor then its not much of an improvement & I dont think the extra mpg it may or may not give would be worth it.