Re: E15 and our Jeeps
We have several stations here that only carry gasoline that contains up to 15% ethanol and it seems to do okay. I'd say the only negative effects that I could see would be lower fuel economy because ethanol evaporates and burns faster and seems like it would dry out engine components, increasing friction between pistons and cylinders, etc.
I did use E85 in my '14 WK2 and I probably wouldn't do it again simply because I went from getting about 420-430 miles to a tank to right around 330-340, if that. It's a tad cheaper than regular gasoline, but not enough to justify the loss in fuel economy. My WK2 did perform a little better, though.
2011 Jeep Wrangler Unlimited Rubicon
2014 Grand Cherokee Limited 4x4 3.6L Deep Cherry Red