Much like a duck is able to walk, swim and fly while not being so remarkable in any of those, so is an average flexfuel engine when it comes to run on both ethanol and gasoline. But anyway, since flexfuel engines have been more frequently based on the less-sophisticated gassers of each manufacturer, maybe they could fare better if based on more advanced ones which could have parameters other than simply injection flow and ignition timing shifted on-the-fly according to the fuel in use to get better efficiency with both (or with various blends).
https://engineeringworkarounds.blogs...l-capable.html