E85 Fuel - Can I add Some in my non E85 Car?

Factual Questions
1

I know from internet searches that E85 cannot be used repeatedly in a car not designed for it because of corrosion issues.
I also read that accidentally filling your tank once should not hurt your car.

What I cant find an answer to is this:

  1. Will small amounts of E85 added with each fill up of regular gas hurt the car? Let’s say a 9 to 1 ratio.
  2. Would I see a fuel efficiency increase, decrease or no change?
2

Don’t know about #1, but I have driven a car that is designed to take either regular gasoline or E85, and it gets worse mileage with E85 than with regular gas, so I would presume that you would get worse mileage.

3

The energy content of E85 is 72% that of pure gasoline, so your 29 MPG car is only going to get 21 MPG with E85. Instead of 290 miles on a tankful, you’re only going 210 miles. Of course, the fuel tax is still the same per gallon, so it’s effectively a 39% jump in road tax (per mile). At a Shell station in Charlestown, MA, the E85 price is only 13% lower than the gasoline price, for a net increase of 20% in cost-pre-mile. Anyone who buys E85 with the thought of saving money has not done their homework.

4

1, Most cars these days can handle E15, so if you mix E85 and regular fuel (probably E15 in most areas these days) in a 9 to 1 ratio, the ethanol concentration is still going to be low enough that I wouldn’t expect any major problems from it.

  1. Your mileage will definitely decrease, as bizerta’s post explains.

I have to ask, though. Why on earth would you think that this would be a good thing to do?

5

Unless you’re filling up with E85 before returning a rental car. :slight_smile:

6

Is this another alias for the doper that was going to run deisel in a rental car?

7

Thanks all this is exactly what I wanted to find out. My goal is to maximize the mileage of my 2011 Ford Focus. Through driving adjustments and proper tire inflation I’m up to a stable 35 MPG. I was thinking maybe a little E85 could boost it a few and lower my emissions too. Looks like that’s not the answer though.