Why More People Drive Alone, Despite High Gas Prices

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Here is one that will make you scratch your head. Despite a huge increase in the cost of gas since 1970, a new study by the University of Michigan showed that more people are driving alone. It's the latest reflection of how driving in America has changed over the last 43 years.

"We value the flexibility of driving alone more than the potential savings in the cost of gasoline," said Michael Syvak, Director of Sustainable Worldwide Transportation at the University of Michigan Transportation Research Institute. According to Syvak, the average number of people in vehicles has dropped from 1.9 in 1970 to 1.38 in 2010. A number of factors contributed to that change, including the growth of women entering the work force—so there are more American homes with two cars and two drivers heading to two different job locations.

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In 1970 the average price for a gallon of gas was 36 cents. By 2010, the average price was $2.79 per gallon.

More MPG Means More Driving

As cars and trucks have become more fuel efficient, Americans have changed their driving habits. In short, we're driving more. "This is the so-called rebound effect," explained Syvak. "If we drive a vehicle with good fuel economy, we feel that we are still ahead in terms of the operating costs even if we drive it a bit more than a vehicle with poor fuel economy."

In other words, we're driving more because we feel our cars and trucks are going further on a gallon of gas. In fact, the fuel efficiency of our vehicles is far better now than it was back in 1970.

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In 1970, the estimated average fuel economy for vehicles on American roads was about 12 miles per gallon. By 2010, thanks to Washington aggressively pushing for better fuel economy, the average vehicle on the road got roughly 17 MPG.

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That may not seem like much of a change, but keep in mind that's for all vehicles. Strip out commercial trucks and the fuel economy gains are even greater. In February, the average fuel economy for new cars and trucks sold in the U.S. hit an all-time high of 24.5 MPG.

—By CNBC's Phil LeBeau; Follow him on Twitter @LeBeauCarNews

Questions? Comments? BehindTheWheel@cnbc.com

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