full tank of gas is to heavy use maybe 5 of gas and 1 &1 1/2 of e 85 the % of the ethanol is + to the E # e 10 is 10% ethanol and e-85 is 85% so set yours around 33% and your car can take it not sure with a tune and pulleys my C320 has a afr reading of 10.2 and with the 33% it reads 11.8 ,,which is good NOT LEAN my black V8 the afr's were in the low 12's could not add anything over e15 in it. good luck,, maybe we have come up with some cheap hp and only need it when we want to go fast... jim