Experiment shows MPG improvement easier than you think

A 9.3 percent improvement in fuel economy might seem to be a solid win in Rich Patterson's $500 truck mileage experiment.

Patterson, director of the Indian Creek Nature Center, ordered up a healthy serving of maintenance on his 2005 Chevrolet Colorado pickup truck on May 4, including new tires with lower rolling resistance and synthetic motor oil. He also filled his tank after the service work from ethanol to Top Tier detergent gasoline, which is supposed to get better fuel economy.

The fuel economy results after the changes worked out to 26.11 miles per gallon versus 23.88 miles per gallon before the work.

Patterson believes the experiment certainly shows it's possible to use ordinary maintenance work to improve fuel economy, even though he doesn't stand by the results as scientific.

“It's always iffy comparing fuel efficiency as conditions are never quite the same,” Patterson said. Air temperatures were higher during the after-maintenance test, for instance, possibly affecting mileage.

Jeremy Tinder of Mount Vernon Road Tire Co. recommended the maintenance work, which included the removal of a small roof rack to reduce aerodynamic drag, and replacement of the differential fluid, which had presumably lost some of its viscosity with age.

Tinder said he wouldn't have liked to see a 10 percent improvement in fuel economy, but the exact percentage change doesn't really matter.

“You can debate what kind of effect the work we did had on the fuel economy, but it obviously had a positive effect,” Tinder said.

Patterson agrees. If everyone with a motor vehicle could improve their fuel economy by 1 percent, he said, it would result in vast reductions in oil and gasoline consumptions, resulting in lower oil prices and fewer air emissions.

Ironically, the big improvement Patterson had hoped to achieve was not possible. He wanted to buy low-rolling resistance tires designed to boost fuel economy, but they were not available in the size needed for his truck. He instead bought tires with a lighter tread that should have had a more slight beneficial effect.

Tinder said low rolling resistance tires alone may improve fuel economy by 6 percent.

If any other changes could have been made, Tinder would have changed the power steering and transmission fluid. He said they become less viscuous with age, requiring more power from the engine.

The price of mid-grade ethanol across Iowa averaged $3.64 per gallon on Wednesday, according to AAA. Gas prices averaged $3.75 per gallon nationally after pushing the $4 mark earlier this spring.

Patterson said the new tires made up by far the largest share of the roughly $500 bill for the project. He said most of the other work, like replacing the differential grease, replacing the motor oil and replacing the filters would all have been needed anyway.

Regular gasoline costs about a dime more per gallon than ethanol, Patterson said, but provides better mileage that at least offsets the cost.