Just completed a trip across NI, Antrim Coast and the Republic of Ireland, about 850 miles mostly in heavy rain and strong winds mostly on E5 petrol with a heavily laded car, I started out with a tankful of E10 and filled up with E5 as we went along. I experienced about 2 to 3 miles per gallon more on the E5, but much was on deserted country roads. More noticeable was the increased sweetness in the engine note, it certainly liked E5 more than E10.
