Ethanol is higher octane than normal gasoline so it "should" work without preignition, etc... however it can dissolve and loosen deposits in the fuel system, which on older cars usually turns into a clogged fuel filter and needing to drain the tank at minimum.  Some seals and gaskets can be dissolved by high enough percents of ethanol, and that's no good either.

But yeah ethanol is comparable enough to gasoline that it will usually work, if you can keep it delivered to the engine.