So it's been 10,000 miles since I started this experiment of mixing E85 with straight 87 octane gasoline (E10, really) to make a higher ethanol content blend. I've averaged about E30 during this time, going as high as E40. I have not had one drivability or reliability issue. Not one.
Again, this car is a 2004 Acura TL with 150k miles on it to start. It is not a flex fuel vehicle, not specifically designed for high ethanol blends.
There is a lot of misinformation on the 'net about what E85 does to non-flex fuel cars. Let this blog be evidence that modern cars can easily handle higher ethanol blends (E15, E20, E30), if not straight E85. By modern cars, I mean everything after, say, 2001.
Considering that the average car is 11 years old, we are rapidly moving to a vehicle fleet that could handle a lot more ethanol in the fuel than is currently available. If more retailers had E85 and blender pumps, and if the blends were priced fairly, a lot more ethanol could be sold in fuels than is currently the case.