E10 is less fuel efficient than E5 so less mpg. I will continue with super unleaded even though it carries a price disadvantage. Found that my mk6 had less soot on the exhaust tips with 99 Octane.
Ethanol only has about 70% of the energy density of petrol, so E10 is about 3% less energy dense than petrol with no ethanol added, not a huge deal.
Pure ethanol has,a RON number of about 109. For those cars that are designed to run on ethanol, they run on a significantly higher compression ratio as they need a lot more fuel in per ignition cycle. If they had the growing space fir our food requirements and sugar beet/cane for fuelling, running cars on ethanol would be the eco way to go.
