Wow, talk about post resurrection.

Here's how I got 22%. Key assumptions:
1) 19.3 gallon tank
2) E85 is 85 percent alcohol

5 gallons of E85 is 4.25 gallons of alcohol.
4.25 gallons of alcohol mixed into 19.3 gallons total volume is 22% alcohol by volume.

It could be an even higher percent as our regular gas often has an unknown percentage of alcohol up to 10 percent.

How did you get 4%? New math? <img src="/forums/images/graemlins/wink.gif" alt="" />