Fuel economy up, but consumption up even more

March 6, 2013

(Phys.org) —Although vehicle fuel economy has improved 40 percent since 1970, the total amount of fuel used has increased by more than half, says a University of Michigan researcher.

Using data from the U.S. from 1970 to 2010, Michael Sivak of the U-M Transportation Research Institute examined the impact of changes in vehicle fuel economy, distance traveled and vehicle load (number of occupants) on and the potential effects of future changes on reductions of fuel used for personal transportation.

Sivak found that during the 40-year period, vehicle distance traveled increased 155 percent overall, but because vehicle load fell 27 percent, occupant distance traveled rose only 84 percent.

Vehicle fuel economy (of the entire fleet of light-duty vehicles) improved from 7.7 gallons/100 miles to 4.6 gallons/100 miles. However, because of the decrease in vehicle load, occupant fuel economy improved by just 17 percent.

"As a consequence of the changes in vehicle fuel economy, vehicle distance traveled and vehicle load, the total amount of fuel used increased by 53 percent," Sivak said.

Looking forward, Sivak said that a 20 percent improvement in fuel economy for the entire would result in an 18 percent drop in the amount of fuel used—due to a in which about 10 percent of the gain in fuel economy would be lost due to an increased amount of travel.

"Importantly, however, changes in fuel economy of take a long time to substantially influence the fuel economy of the entire fleet," he said. "This is the case because it takes a long time to turn over the fleet. Consequently, an 18 percent reduction in fuel used by vehicles purchased in a given year—due to a 20 percent improvement in their fuel economy—would result in only about a 1 percent reduction of the fuel used by the entire fleet.

"The required long lead time to substantially influence the fuel economy of the entire fleet has been used to argue that policy emphasis should be on reducing vehicle distance traveled through an increased fuel tax—which would have an immediate fleet-wide effect."

Explore further: Fuel economy of new vehicles still at lowest point in the past year

More information: deepblue.lib.umich.edu/bitstream/handle/2027.42/96632/102926.pdf

Related Stories

New vehicle emissions show record improvement

October 5, 2012

Emissions from new vehicles are down a record 20 percent in the last five years, say researchers at the University of Michigan Transportation Research Institute.

Better fuel economy: Billions and billions saved

October 16, 2012

(Phys.org)—As fuel economy of new vehicles improved 18 percent over the past five years, billions of gallons of gas and billions of pounds of emissions have been saved, University of Michigan researchers say.

Fuel economy at all-time high, researchers find

November 6, 2012

(Phys.org)—Fuel economy of all new vehicles sold in the United States is at its highest level ever, say researchers at the University of Michigan Transportation Research Institute.

Recommended for you

Interactive tool lifts veil on the cost of nuclear energy

August 24, 2015

Despite the ever-changing landscape of energy economics, subject to the influence of new technologies and geopolitics, a new tool promises to root discussions about the cost of nuclear energy in hard evidence rather than ...

Smart home heating and cooling

August 28, 2015

Smart temperature-control devices—such as thermostats that learn and adjust to pre-programmed temperatures—are poised to increase comfort and save energy in homes.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

CapitalismPrevails
1 / 5 (2) Mar 06, 2013

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.