Con-way Freight is slowing down its 8,400 trucks to curb its gas consumption and carbon emissions.

The transportation company says it turned back the speed governors on all the vehicles in its fleet, allowing the truck engines to run at 62 miles per hour at most instead of the previous maximum of 65 miles per hour.

Con-way estimates it will cut its diesel fuel use by 3.2 million gallons a year and its carbon dioxide emissions by 72 million pounds. The company estimates it uses 100 million gallons of gas a year.

The switch is part of Con-way’s commitment under the voluntary SmartWay Transport Program, a partnership between the U.S. EPA and freight industry businesses with the goal of reducing carbon emissions by 33-66 million metric tons and nitrogen oxide emissions by 200,000 tons by 2012.