All the gas where I live is 10-15% ethanol and I've never had trouble. Modern engines (anything within like 25 years at least) is designed to run with a bit of ethanol, doesn't hurt anything at all. Not E85 though, its 85% ethanol, and only for "flex fuel" cars or whatever. I don't remember the max ethanol allowed but I'm sure its in the manual, probably 10 or 15%.

My mk6 is stock, coming up on 100k miles, and I drive it hard. WOT, up and down the gears, stomping on it in traffic and stuff, E10 doesn't bother it a bit, I never log misfires or timing retards.

Octane rating is important though, 91 is what we need, whether it has ethanol or not.