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10:11 am
Tue June 7, 2011

Drivers have big impact on gas mileage

When it comes to fuel economy, Roger Clark says, "how you drive matters."

Roger is a fuel economy expert with Chevrolet. He has a few tips for getting more miles per gallon without buying a new car. We tested his driving style against Monte Doran’s, also with Chevy. Roger and Monte drove matching Chevy Cruzes and took identical routes. Both did a little highway and a little city driving on a weekday around 5pm. Roger followed his own fuel saving tips and Monte did exactly the opposite.

Roger says the number one factor in fuel efficiency is the way you drive. Drivers should pay attention to the cars around them and try to coast more often:

“That helps your fuel economy tremendously because when you’re looking ahead, you don’t have to break as often, you can leave a good safe distance.”

And take note—Roger said speeding is a bad idea if you want to save gasoline:

“Between 40 and 50 [miles-per-hour], every car gets its absolute best fuel economy cruising at a steady speed. So for every ten miles per hour above that, you actually lose four miles per gallon. It’s a huge amount.”

So that means that when you’re going 80 on the highway, you’re losing 16 miles per gallon. At the other extreme, sitting idle in traffic isn’t good for fuel economy either. It’s kind of hard to avoid city driving, but Roger says if you know another route with fewer stops, even if it's longer, you should take it.

Even the wait at a drive-thru window or a train-crossing can use a lot of gas. In fact, "for every 15 minutes of waiting, you've used about a quarter of a gallon" says Roger.

And there are a few things drivers can do before they even start their engines. Your driving habits do account for most of your miles-per-gallon. But Roger says the next biggest factor in fuel economy is aerodynamics, especially at highway speeds.

A common mistake is having flags or a bike rack on top of your car. And a third point—Roger says don’t drive around with a bunch of stuff in your trunk. In the “bad” test car, Monte left 6 bags of rock salt in the back. That extra weight isn’t going to help your miles-per-gallon.

You should also check your tire pressure because low pressure can negatively affect your gas tank. Roger said it’s important to check it whenever the weather changes because tire pressure is very sensitive to temperature.

I also asked Roger one of the most common questions about fuel economy…to run the air conditioning, or not. He says:

“The best thing to do with your air conditioning is, if you’re above 40mph, go ahead and use your air conditioning because it turns out that rolling your window down above 40mph actually uses more fuel than your air conditioning would.”

There are a few things that don’t help. Roger doesn’t put much stock in fuel additives or changing air filters when it comes to fuel economy, but they might be necessary for routine maintenance in your vehicle. He was also pretty adamant that premium gasoline won’t help you get more miles-per-gallon.

At the end of our ride, Monte, who drove the “bad” car, compared his miles-per-gallon with Rogers and mine after we drove the “good” car:

On Rogers drive, he got thirty miles per gallon on that trip, which compares to mine at 19.7 miles per gallon. Which means he got about 50% better fuel economy than I did.

So if you want to get more miles to the gallon during your typical commute: pay attention when you’re driving, don’t speed, leave the car flags and bike racks at home, and lighten the load in your trunk. But you don’t have to take my word for it. Roger says:

“If you wanna drive in a sporty way, go ahead and do it, but know that you’re using a lot of gas .”

-Bridget Bodnar, Michigan Radio News.