General Motors knows a thing or two about helping save consumers money at the pump. In fact, the automaker’s recent string of fuel-efficient vehicles helped to boost sales last month, even as the price of gas topped $4 per gallon.
Aside from its fuel-efficient lineup, GM has also offered consumers some tips to help improve fuel economy. To validate these tips, a pair of GM engineers recently drove two identical compact cars on a typical workday commute. The results show that sweating the small stuff could save drivers as much as $100 a month at the pump.
Two identical Chevrolet Cruze LTs — which the EPA estimates get 24 mpg city, and 36 mpg highway — were driven for 20 minutes, including city and highway driving as well stops for coffee. One vehicle was a properly maintained Cruze, while the other ignored common maintenance and drove inefficiency. The results speak volumes:
| Ann Wenzlick drive | 37 mpg | 575 mi per tank | $1,621per year |
| Beth Nunning drive | 21 mpg | 325 mi per tank | $2,857 per year |
| Savings | 40 percent | 250 mi per tank | $1,236 per year |
Here are five things Ann Wenzlick did to drive more efficiently in her Cruze:
- Get out of the drive-through lane
“While Beth waited in the drive-thru with her car running, I shut off the engine and went inside for my morning coffee. Idling for 15 minutes burns through an average of a quarter of a gallon – adding another $1 to the cost of your latte.” - Easy on the accelerator
“In the city, I accelerated smoothly while Beth demonstrated one of the most common mistakes we see on the road: Jumping on the gas at every light, only to hit the brakes as she caught up with the traffic ahead. Such aggressive driving isn’t going to get you home any faster, while driving smoothly can improve your mileage by 20 percent.” - Driving 70, not 80
“On the highway, I drove 70, compared to Beth’s 80. Again, a 10-mph difference likely won’t add much time to your daily commute, but it will save you up to four miles per gallon on the highway.” - Use cruise control when possible
“I tried to maintain a constant speed during our drive, while Beth’s fluctuated with traffic. Try using cruise control when possible, and maintaining a constant speed over time, which is much more efficient than speeding up and slowing down over and over again.” - Keep the windows rolled up
“One of the most common questions we get is ‘Is it better to drive with the A/C on, or off?’ At slower speeds, turning off the air conditioning can save you a little, but I always roll up the windows on the highway. Beth was driving with her windows down, and the increased air pressure acted like a parachute trying to slow her down – consuming much more energy than air conditioning ever will.”
Here are things that contributed to Beth Nunning’s poor fuel economy. Washington DC Chevrolet dealers regularly warn customers of these conditions:
- Low tire pressure
“All four tires on my car were five pounds under their recommended air pressure. That’s not enough to change how the Cruze drives, but it does make the engine work much harder to turn the wheels. Check your tires at least once a month, as a tire that is 10 pounds under pressure can cut your fuel efficiency by more than 3 percent.” - Using roof ornaments and/or roof rack
“To show support for my Detroit Tigers, I put up window flags on my Cruze for every home game. But, when the boys hit the road, the flags will come down. At highway speeds, up to a third of your fuel is used to overcome wind resistance, so even small changes to your vehicle’s aerodynamics will have a big impact in fuel economy.” - Carrying unnecessary cargo in the trunk
“I had six bags of water-softener salt in the trunk I bought on sale at the hardware store. But, according to EPA estimates, every 100 pounds of weight can reduce fuel economy by 2 percent. While I saved at the checkout, that 240 pounds of salt added almost 5 percent to my fuel costs for the trip.” - Ignoring the “check engine” light
“I called OnStar to run a remote diagnostics check on my Cruze, because the check engine light was on. Turns out the light was on because the gas cap was loose. But, more serious engine problems can cut your fuel economy by up to 40 percent.” - Not planning errands efficiently
“An engine at operating temperature is up to 50 percent more efficient than a cold engine. So, when possible, it’s much better to run five errands in an afternoon, than running one errand every day of the week.
“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.
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