Fuel economy by the numbers

Save money on high gas prices with fuel economy tips from GM fuel economy experts

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Simple changes to driving habits can have a big impact on fuel economy, saving you money by burning less fuel, and decreasing the negative environmental impact from driving.

It's the start of summer driving season, and along with it will come the annual hike in gasoline prices. GM has helpfully provided some tips to increase fuel efficiency that will not only save money, but decrease the negative environmental effect of driving a gasoline powered car. The best part is that you don't have to geek out on hypermiling techniques, nor do crazy things to your car to improve its aerodynamics.

Two of GM's fuel economy experts, Ann Wenzlick and Beth Nunning drove identical Chevrolet Cruze LTs, but used different driving techniques to demonstrate the improvements you could see with a few simple behavioral changes. The Cruze has an EPA estimated at 24 mpg city and 36 mpg highway. The two drove along identical routes, that included both city and highway driving, a stop for coffee, all in an attempt to mimic a typical morning commute.

Ann Wenzlick drove using efficient driving habits, and achieved 37 miles/gallon efficiency. Beth Nunning, on the other hand, drove with a lead foot and did other inefficient things, achieving a paltry 21 miles/gallon efficiency. The difference between 37mpg and 21mpg, on the same car, is enormous, a full 40 percent difference in results. Where Wenzlick would get 575 miles of driving per tank of fuel, Nunning would get only 325 miles.

The fuel efficiency differences spread out over a year of driving would mean that Wenzlick would spend $1,621 per year on gasoline, while Nunning would spend $2,857 per year. By driving inefficiently Nunning's habits are costing her $1,236 per year in excess fuel purchases. GM's figures don't show this, but it also means her personal environmental impact is that much worse than Wenzlicks.

“Ann and Beth’s results support data from OnStar that shows the fuel economy of drivers in identical cars can vary by 75 percent,” said Roger Clark, manager of the GM Energy Center. “With a well-maintained car, the best drivers get up to 25 percent more miles per gallon than average. When you combine a poorly maintained car with inefficient driving habits, the fuel economy of the worst drivers can be 50 percent below average. The fuel economy of every vehicle is greatly affected by how you drive, and how you care for your vehicle. Often, relatively small changes to your driving habits and vehicle maintenance can make the difference between being on the bottom, or the top, of the fuel-economy scale.”

Wenzlick and Nunning provided some tips

Get out of the drive through lane: The test route involved stopping at a coffee shop with a drive through window. While Nunning went through the drive through line, Wenzlick parked, shut off her car, and walked inside the shop. The idling engine can burn through a quarter gallon of gasoline in 15 minutes, adding significantly to the cost of buying the coffee. Note, though, that an electric car driver doesn't see this extra cost, because electric cars do not idle when sitting still, and would not waste energy while going through a drive through lane.

Take it easy: Wenzlick accelerated smootly, while Nunning made jack-rabbit starts and otherwise drove with a lead foot. Her aggressive driving style is what resulted in the lower fuel efficiency rating. There are more hypermiling techniques along these lines, such as if you see a light turning red ahead of you, take your foot off the gas and coast to the light, rather than keeping the accelerator going and braking at the last minute.


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