2011 Buick Regal w/ 2.4L engine, the NA Ecotec. Gassed up two weeks ago at a local station which trumpets "Ethanol Free!" Only saw 23.05 mpg, about the same as I got on the E10 I fed it at Walmart a few weeks back. Occasional A/C use might have knocked the mpg down some.
Gassed up today at another "ethenol" free station, but he's worked a new wrinkle for this area: E0 premium at nearly 4.00, E10 regular at 3.48, but E0 regular at, get this, 3.80. That's about 10% higher, and the most I've ever seen with E0 over E10 is a 10% increase, so I shrugged and went with E10. If nobody else in my area has reasonably-priced E0, I suppose I'll be going with E10 -- probably Walmart, as the cheapest.