Automobile(s): Crystal Red 2008 CTS FE2, Pearl 2010 ESV Plat
Ok, so I take it you want it for the power gains? It would cost too much to make it work with e85. You would be better off getting a turbo or supercharger. Im sure you have seen the GTR, Veyron, CCX, Viper and so on all tuned on E85. They had lots of work done to make them work on corn.
You actually CAN run E85 with no modifications other than an ECM flash/tune from us. We have several 3.6 Camaros doing it. TeamZambo is correct that you CANNOT run E85 without extensive fuel system modifications on most cars, but that doesn't apply to the 3.6DI motor because it's direct injected. I could set you up with a 100% E85 tune for $315 if that's all you plan to run. If you want a regular fuel tune and an E85 tune, $415 total.
It's still a night and day difference, even on regular fuel.
Just keep in mind- if you have the E85 tune on the car, it will NOT run on regular, other than maybe idling around a parking lot. And even then I wouldn't recommend it. And if you have the regular fuel tune on the car, same story. You can't put E85 in it and expect it to run. Running E85 requires much more fuel and your injectors won't be set up to deliver it on the regular tune. You would have to get 95% of the regular fuel out, go to the gas station with the laptop, upload the E85 tune, and fill up with E85. Same if you wanted to switch back.
There just isn't a way to detect the alcohol content on this car. We actually do have the ability to do so on the cruze with the 1.4T. We can use the virtual alcohol sensor built in to the ECM to determine ethanol content and adjust accordingly. I wish it were available on these cars as well.