What would happen if you threw say... 4 gallons into the 21 gallon tank? Is it bad for the fuel pumps/fuel lines? Do these engines not like E85? I don't see any tuning companies boasting about it, which leads me to believe it's a very bad idea/useless. I'd like to figure out + understand why some platforms respond well to E85 and some don't?

 

Found it. https://mbworld.org/forums/w213-amg/...heir-e63s.html