I recently tested a known brand of premium unleaded versus a cheaper brand of ethanol-based premium unleaded in my motorcycle. I got a 23 percent reduction in fuel economy on the ethanol-based fuel over two full tanks but no noticeable drop in performance. However, the savings in fuel cost per liter does not add up – I'm better off spending more on the expensive fuel... Why is this? Can fuel mapping or tuning help here?

I am not sure who started the ethanol based fuels, but in the states it was mandatory in the winter months to help with Air pollution. It was 10% ethanol based, however cars used 10% more fuel or to say got 10% less MPG or km/l as it may be. Was it the farmers that grew Corn ? No idea, but now it seems to be spreading, and I too get about 10% better km/l using regular unleaded than the ethanol based fuels. Doing the math the whole thing just does not add up.

When you say premium do you mean 95 octane (no ethanol) or 91 octane, most of which is now 10 percent ethanol. The higher octane is for high compression engines – it stops them from pinging of detonating and suits most motorcycles. Did you make a real effort to listen for pinging while riding with your helmet and all that wind noise – try fifth gear 60km/h small roll on? It's like listening for a snake...

The adding of ethanol reduces the density of the fuel, therefore the fuel system passes more of it (there goes your fuel economy) but the ethanol gives a bigger bang and keeps the power up and every one likes that. The side affects of ethanol in a motorcycle that wasn't built to use this fuel are sneaky and will catch up with the motorcycle eventually. You will benefit in more ways than one by using 95 octane fuel and a custom mapped fuel map to tune you motorcycle.

Hello James,
I can confirm your experience with ethanol-based fuel E10. My scooter takes 10 percent more per km even though it is ready for E10 and has FI.
This is an invention of politicians to have a green or good conscience but at least it is a swindle.
You can take a look to all the discussions they have now in Germany about that theme. But the same you can say about all the unleaded fuel.
The only reason for all this is a wrong thinking in green positions and everybody allover the world has to pay for this because we're burning food in our cars and motorcycles.