My wife and I purchased a new 2009 Chevy Suburban in March to replace our old Suburban. With 6 kids, we need to have some space to haul them and luggage around. The minivans on the market don't have enough luggage room, and the full size vans sit higher and don't seem as stable while driving. I was glad to see that the one we purchased had the ability to use E85. Last summer when gasoline was over $4 per gallon, I was wishing I had the option. I had read plenty of business articles about E85 and knew that the gas mileage was lower. Most of the articles stated there was a 15-20% difference in gas mileage. But the real world is where I live, so of course I had to put the figures to the test.

The Suburban we purchased has an information center that keeps track of air pressure in all 4 tires (which is really cool, by the way), average gas mileage, instantaneous gas mileage, and fuel range. I knew from the average gas mileage calculations that we were currently getting 15.4 mpg. This was on regular unleaded 87 octane gasoline and was based on a mix of about 5,500 miles of highway and city travel. When the gas prices started going up recently, there came a point when gasoline was $2.39 per gallon and E85 $1.99 per gallon which is a 20 percent difference.

So, to put the numbers to the test, we let the tank get to about one-eighth full and filled up with E85. We recorded the number of gallons to fill the tank and noted the mileage. We then did our daily driving around the city. We also ended up with some highway miles since we had been planning a 2 hour trip into northern Indiana and Illinois. We filled up again in northern Indiana with E85 and recorded gallons and miles.

Ultimately, based on 3 tankfuls of E85 and about 1,200 miles, we were able to conclude that for us, based upon our driving patterns and style, we can get about 12.1 mpg with E85. As it turns out that figure is about 78% of the total mpg we can get with regular unleaded gasoline, which is a little bit less than the numbers based upon my reading, but still close. We concluded that anytime E85 is $0.25 less per dollar than gasoline, it would be cheaper to purchase. If not, it is more economical to go with gasoline.