U-M's Michael Sivak says flying is not only safer than driving, but it's also more environmentally friendly.

If you are thinking of taking a road trip this summer, you might want think again…at least if you’re concerned about the impact on the environment.

University of Michigan Researcher Michael Sivak has concluded that flying is not only safer than driving, but it’s also greener.

“Although the fuel economy of new vehicles is continuously improving, and these improvements are likely to accelerate given the recent update to the corporate average fuel economy standards, changes in fuel economy of new vehicles take a long time to substantially influence the fuel economy of the entire fleet,” said Sivak, a research professor at UMTRI and director of Sustainable Worldwide Transportation, a research consortium that addresses major road transportation issues worldwide.

It takes twice as much energy to drive than it does to fly, he determined, after examining trends in energy intensity — the amount of energy needed to transport a person a given distance — in light-duty vehicles versus domestic airline flights. His analysis measured British Thermal Units (BTU) per person mile from 1970 to 2012, he said.

Sivak found that the energy intensity of driving is 2.07 times that of flying. In 2012, BTU per person mile was 4,211 for driving compared to 2,033 for flying. Consequently, the entire fleet of light-duty vehicles would have to improve from the current on-road fuel economy of 21.6 mpg to 44.7 mpg for driving to be as energy intensive as flying.

The 16.5 million light vehicles sold in 2014 accounted for only about 7% of the entire fleet of light-duty vehicles on the road, Sivak said.

“It is important to recognize that the energy intensity of flying will also continue to improve,” Sivak said. “Consequently, because the future energy intensity of flying will be better than it currently is, the calculated improvements underestimate the improvements that need to be achieved in order for driving to be as energy as flying.”

Last year, Sivak issued a report that compared energy intensities of flying and driving from 1970 to 2010. The current study not only extends the analysis through 2012, but also fuel calculations for flying exclude fuel needed to transport paid freight and mail on passenger carriers and on all-cargo carriers.

Meanwhile, the mileage of new vehicles sold in the U.S. ticked upward last month, according to researchers at the University of Michigan Transportation Research Institute.

(U.S. gasoline usage at lowest levels since 1984. For more, Click Here.)

Average fuel economy window-sticker values of cars, light trucks, vans and SUVs purchased in March was 25.4 mpg, up from 25.2 mpg in February and the same rate as a year ago.  The change likely reflects the increased gasoline prices from February to March, said Sivak.

(Click Here for details about Ford’s Q1 earnings.)

“The average fuel economy during the first six months of this model year has stayed the same — 25.3 mpg — as during the preceding 12 months,” Sivak said. Overall, vehicle fuel economy is up 5.3 mpg from October 2007, the first full month of monitoring.

(To see the Queen of Green telling makers to stop crying about 54.5 mpg, Click Here.)

In addition to average fuel economy, U-M issued a monthly update of their national Eco-Driving Index, which estimates the average monthly emissions generated by an individual U.S. driver. The EDI take into account both the fuel used per distance driven and the amount of driving — the latter relying on data that are published with a two-month lag.

During January, the EDI remained at 0.82 (the lower the value, the better) for the second straight month. The index currently shows emissions of greenhouse gases per driver of newly purchased vehicles are now down 18%, overall, since October 2007.