Will Gasoline Edge Out E10 in Fuel Economy Test?

By: Dana Brueck
By: Dana Brueck

Some see ethanol as one way to boost agriculture or contribute to our nation's energy independence. One local man has dedicated his career to finding alternatives to gasoline. He helped us put E10 to the test in the second part of our series "E10 on Trial."

Previously we showed you how the test was conducted. In this second part, we share the results.

Fill the tank, weigh the tank and repeat.

In the first part of E10 on trial, we showed you how UW Automotive expert Glenn Bower calculated the density of pure gasoline and E10.

NBC 15 then joined Bower as he traveled 62 miles on each fuel, weighing the fuel tank before and after each run.

"Weight is the most accurate way to do fueling," Bower says.

His calculation of fuel used, in pounds, divided by density shows the truck used 5.35 gallons of pure gasoline.

But Bower wants to know the fuel economy. He takes the distance traveled of 62 miles divided by the fuel volume in gallons, 5.35.

The result is 11.58 miles per gallon of pure gasoline.
"It seems like a reasonable number to me," he says, "We've got three people in here, equipment in the back. We're traveling at 65 mph."

So is E10 up to the challenge of scoring better, or will it score worse? Remember, before the test, Bower predicted E10 would deliver fewer miles per gallon.

"I would say probably we're gonna see a three to five percent decrease in fuel economy with the E10 blend."

Again, Bower takes the fuel used in pounds, divided by density to show the truck consumed 4.51 gallons of E10. Sixty two miles traveled divided by 4.51 equals 13.74 miles per gallon.

"This is the part where science gets you because it looks like we used less fuel this way."

Bower's F250 truck got more than 13 miles per gallon on E10 versus 11 and a half miles per gallon on pure gasoline.

"I was a little surprised at the results. I didn't think the ethanol would be that much better than straight gasoline," he says.

A study of fuel economy by the American Coalition for Ethanol last year offers mixed results. It says three different vehicles averaged 1.5 percent lower mileage with E10 compared to unleaded.

"It may just depend on the vehicle itself," Bower says.

And the coalition's study seems to support that idea. Bower also says variations in the base fuel could impact the results. He used a winter blend of E10.

"The fuel properties, the amount of energy per gallon does have a window in standards, so it can change summer to winter and that may be one thing that happened today."

Whatever the fuel economy, proponents of ethanol claim it saves customers money because it's generally lower priced. Bower offers a simpler approach.

"In the end, you'll probably waste more fuel driving to a station that has pure gasoline than if you just bought E10 at your local station."

One final note: generally, all vehicles can run on E10, but E85 requires a flexible fuel vehicle.


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