For What its worth....
E85 is usually used in engines modified to accept higher concentrations of ethanol. Such flexible-fuel engines are designed to run on any mixture of gasoline or ethanol with up to 85% ethanol by volume. The primary differences from non-FFVs(flexible fuel vehicles) is the elimination of bare magnesium, aluminum, and rubber parts in the fuel system, the use of fuel pumps capable of operating with electrically-conductive (alcohol) instead of non-conducting dielectric (gasoline) fuel, specially-coated wear-resistant engine parts, fuel injection control systems having a wider range of pulse widths (for injecting approximately 30% more fuel), the selection of stainless steel fuel lines (sometimes lined with plastic), the selection of stainless steel fuel tanks in place of terne fuel tanks, and, in some cases, the use of acid-neutralizing motor oil. For vehicles with fuel-tank mounted fuel pumps, additional differences to prevent arcing, as well as flame arrestors positioned in the tank's fill pipe, are also sometimes used.
Modern cars (i.e., most cars built after 1988) have fuel-injection engines with oxygen sensors that will attempt to adjust the air-fuel mixture for the extra oxygenation of E85, with variable effects on performance. All such cars can burn small amounts of E85 with no ill effects. Operating fuel-injected non-FFVs ) on more than 50% E85 will generally cause the check engine light (CEL) to illuminate, indicating that the electronic control unit (ECU) can no longer maintain closed-loop control of the internal combustion process due to the presence of more oxygen in E85 than in gasoline. Once the CEL illuminates, adding more E85 to the fuel tank becomes rather inefficient. For example, running 90% E85 in a non-FFV will reduce fuel economy by 33% or more relative to what would be achieved running 100% gasoline. (This example is illustrated above in the previous section - the 1998 Chevy S10 pickup experiment.) Even more importantly, continuing to operate the non-FFV with the check engine light (CEL) illuminated may also cause damage to the catalytic converter as well as to the engine pistons if allowed to persist.
IN THE END.......
To run a non-FFV with amounts of E85 high enough to cause the CEL to illuminate risks severe damage to the vehicle, that may outweigh any economic benefit of E85