This is anecdotal, but just wanted to give an example that I've personally experienced.
We used to race go karts with Rotax engines, and the local series organizers decided to mandate 91 octane pump gas ("cost saving measure") as opposed to the VP racing fuel that the engine was designed to use.
The end result was that all the racers ended up having excessive carbon buildup in the cylinder, and would go through several sets of the fuel pump internals every year. The fuel pump is a pulse driven flexible element that the pump gas (containing ethanol) would just destroy.
Never had those issues with the ethanol free VP fuel.
I mean, the need for engine compatibility was part of the push for ethanol, it isn't some big secret, and there are millions of vehicles that have no issues with ethanol gasoline. Blame the organizers, not the ethanol.
All I have are my experiences of every small engine I own that worked fine for a decade or more gradually going to crap in the past few years and I need to take four different ones to the small engine repair guy right now. :)
I’ve just been phasing out every gas engine I own for battery powered. I’m done with gasoline as much as possible. A lifetime of begging this horrible Frankenstein machine we call the internal combustion engine to work is enough for me.
