ANN ARBOR, MI – A new University of Michigan Transportation Research Institute (UMTRI) study evaluated the effectiveness of different methods for reducing light-duty vehicle fuel consumption.

"Driving a light-duty vehicle in the United States is currently more energy-intensive than using a bus or a train and even flying," said Michael Sivak, research professor at UMTRI. "How can we improve on this performance? Vehicle selection has by far the most dominant effect — the best vehicle currently available for sale in the United States is nine times more fuel-efficient than the worst vehicle."

Sivak and colleague Brandon Schoettle studied the effects of decisions that drivers can make to influence on-road fuel economy of light-duty vehicles. The practices they evaluated include vehicle selection and maintenance, route selection, vehicle load, and driver behavior. The researchers said their analysis focused on fuel economy per vehicle, not per occupant. However, the average occupancy of a light-duty vehicle has dropped from 2.0 in 1960 to 1.4 today.

Regardless of vehicle type, vehicles with tuned engines, properly inflated tires, and that use the right kind of engine oil can improve fuel economy by as much as 40 percent.

Choosing to drive on routes that include highways, flat terrain, and less congestion, can cause a fairly dramatic reduction in fuel use. For example, a flat route can yield 15-20 percent better fuel economy than a hilly route. Taking a free-flowing highway route as opposed to a highly congested route can improve fuel economy for that trip by 20-40 percent, the researchers found. In addition, carrying extra cargo (e.g., an additional 100 pounds), can reduce fuel economy by up to 2 percent.

Driving slower and less aggressively can reduce gas usage by 30 percent. Turning off the air conditioner can save up to 25 percent, and using cruise control can save 7 percent at highway speeds.

Source: University of Michigan Transportation Research Institute