I ran 100% gasoline for a while until I got my tune, my car actually picked up 6-8hp on back to back dyno pulls using 10% ethanol over pure gas. I wanted to know if there was a difference in power between the two.
I figured 100% would make more power (it does on my bikes but they have no knock sensors) but it was the opposite with the GT.
Don't know if it's a slight cooling effect of the ethanol or if the computer just likes it better......the 10% stuff may allow for some additional timing.
I know it's somewhat off topic but I just paid $400 to have both my snow blower and pressure washer rebuilt due to ethanol gas. Water settled into the bowl assemblies on both and rusted them out. Now I purchase ethanol free gas, haven't had an issue yet.