I have compiled quite a bit of anecdotal evidence on this subject. I bought a new car 12/92 and asked the service mgr. about using gasohol. His response was that the owner's manual says it's fine as long as the ethanol content didn't exceed 10%, but that the dealership had replaced hundreds of injectors on cars that burned exclusively ethanol blends. His take, which he couldn't prove, was that due to mixing, fraud or stratification, stronger mixes than 10% were finding their way into tanks.
Since then I have run into 10-12 people who drive the same car and had to replace injectors. When I would tell them that I would bet they burned ethanol, every single one responded "Yeah - how'd you know?" I never put it in my cars and have happily gone 200K+ miles with nary an injector issue. An admittedly small sample, but convincing none-the-less.
My other observations are that my son, and several other friends experienced severe vapor lock problems during hot weather while using E10 which vanished completely when returning to full unleaded.
My uneducated take - many, perhaps most, cars can use E10 without problems. Some seem to be more sensitive to whatever problems may be inherent, and so I would tend not to mandate it. Here in Iowa it already has about 80% of the market without mandates. Also, none of my mechanic friends (which is NOT a broad sampling) will put it in their cars.
Mike
