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By Robert Rapier on Sep 10, 2007 with no responses

Wisconsin Tops Minnesota

This is a guest entry from Gary Dikkers who explains that Minnesota and Wisconsin are near twins, except in the category of fuel economy.

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One of my cars is a 1999 GMC Sonoma light pickup truck. Since I got my first driver’s license, I’ve always kept track of miles driven, fuel used, and computed my fuel mileage.

About four years ago I started to notice that whenever I put E10 in my Sonoma my mileage dropped. So I started doing tests — deliberately running the fuel tank to near empty, then filling up with either E10 or straight gasoline, and comparing results.

My Experience Using E10

Time after time, I have arrived at consistently similar results: When I burn E10, I get about 29 mpg at steady highway speeds, and when I burn straight gasoline, I get about 32 mpg.

That three miles per gallon doesn’t sound like much of difference does it? But let’s try a little thought experiment and imagine a theoretical trip of 320 miles.

  • If I use gasoline I would burn 10 gallons.
  • If I use E10 I would burn 11 gallons of that fuel.

But 90% of that 11 gallons of E10 would be gasoline. And what is 90% of 11? A: 9.9 gallons.

That means whether I burn gasoline or E10, I would burn almost exactly the same amount of gasoline on that theoretical trip.

Conclusion

When I use E10 in my Sonoma, I save virtually no gasoline, but I do have to buy 11 gallons of fuel. I now buy E10 only when I need fuel and have no other choice.

Is my truck an anomaly?

I admit my experiments are not scientific. Perhaps my truck is an anomaly, or there is something about the way I drive that causes the difference.

USDOT Statistics

That’s why I found it gratifying when I found a dataset that validates my experience.

Three years ago I discovered that the US Department of Transportation (USDOT), Federal Highway Administration (FHWA) keeps statistics of the amount of fuel burned and miles driven in each of the 50 states.

I live in Wisconsin and happened to know that Minnesota has had mandated ethanol in all their gasoline for the last ten years, while Wisconsin doesn’t. Two very similar states with one known difference — in Minnesota all motor fuels except diesel must be blended to at least E10.

So why not compare the average fuel mileage of the two states? I did, and what was the result?

Results

In 2005 (the latest year for which data is available) Minnesota drivers drove 56.570 billion miles using 2.744 billion gallons of fuel. Their average fuel mileage was 20.62 mpg.

In that same year, Wisconsin drivers drove 60.399 billion miles using 2.592 billion gallons of fuel for an average of 23.30 mpg.

Minnesota drivers actually drove less than their cheesehead neighbors, but used more fuel to do it.

Something caused Minnesota drivers to get almost 12% worse fuel mileage than their neighbors to the east. What could have that been?

Both states have almost identical topography, climate, demographics, and about the same mix of urban/rural driving. (In fact, Wisconsin has a slightly higher ratio of urban to rural miles driven.) The two states are about as close to being twins as any two states could be. (Not counting the Vikings/Packers difference of course.) Yet fuel economy in Minnesota is worse, and their drivers buy and burn more fuel than their neighbors.

The only obvious difference that jumps out is that Minnesota has mandated its drivers burn a blend of ethanol and gasoline — a fuel with a known lower energy density than gasoline.

The facts are pretty clear: The results of this huge sample size – the entire State of Minnesota – validated my individual experience.