Like I said, there is no evidence that putting more than 10% ethanol in your car (E20, E30, E40, up to E85) does any damage. States like Minnesota and South Dakota have "blender pumps" that dispense E20, E30, and even E40, and there are no reports of damage to any fuel system.
The EPA and the automakers are a bunch of scare mongers on the issue. In the end, I blame fear of lawsuits. They know that damage is unlikely, but they can't take the risk that they're wrong.