> and much harder on car engines, even ones designed for it (unsourced, but so my gearhead friends have told me) Bollocks. The energy content is slightly lower

> and much harder on car engines, even ones designed for it (unsourced, but so my gearhead friends have told me) Bollocks. The energy content is slightly lower, but there is zero harm to automobile engines. Your unsourced "gearhead" friends share a common misconception and prejudice against ethanol. There is absolutely no issue with E10 fuel in cars with model years as far back as the '90s, or even earlier. Very old classic cars may have issues with some fuel line components, but even there E10 will not wreck the engine. As a fuel E10 is extensively tested on gasoline autos. Two-stroke engines are another matter. And 2001 and newer autos can run E15.