A relatively simple fuel-efficiency measure - drive slower - was adopted by many truckers in 2008. But that doesn't mean they're putting the pedal to the metal now that fuel prices have fallen.

Con-way Inc. (CNW), a top trucking company, has been sticking with reduced maximum speed limits that it instigated last year as a means of combating spiraling fuel costs.

In a high-profile move, Con-way lowered the top highway speed of its less-than-truckload fleet to 62 miles per hour from 65 last February. In May, it lowered the maximum speed of its long-haul fleet to 65 miles per hour from 70.

Combined, the two measures were projected to save roughly 5.8 million gallons of fuel annually. Trucking companies have electronic engine controls to regulate the top speed of their trucks.

Fuel prices have fallen significantly since, but "we've just left (the speed limits) were they are because fuel eventually is going to increase" again and remains a major expense, Con-way spokesman Gary Frantz said.

The company is maintaining other fuel-efficiency measures put in place last year as well, including stepped up efforts to ensure proper tire pressure and to reduce engine idling times.

Frantz said the actions have resulted in safety and emissions benefits, in addition to improved fuel efficiency, and have had little downsides.

For instance, the slower speeds have tacked 20 to 30 minutes to the longest runs by Con-way's less-than-truckload fleet. But Frantz said the figure has been easily manageable, noting that 2008 on-time performance of 97.1% actually increased slightly from 2007.

Representatives of fellow trucking companies J.B. Hunt Transport Services Inc. (JBHT) and YRC Worldwide Inc. (YRCW) weren't available for comment. But other freight haulers appear to be sticking by stepped up fuel-efficiency measures as well.

Patrick Hiatte, a spokesman for Burlington Northern Santa Fe Corp. (BNI), noted that fuel efficiency has always been a top priority for the railroad, but he acknowledged the issue had a higher profile in 2008 amid the soaring diesel prices.

Burlington Northern's efforts include training engineers to accelerate and break steadily, Hiatte said, because "the quicker you start and the quicker you stop, the less fuel efficient you are."

The company also has worked to reduce locomotive idling times and to optimize train lengths and loads, he said. Longer-term efforts include testing alternative fuels, as well as migrating to more fuel-efficient locomotives.

While the issue of fuel-efficiency clearly took on "heightened awareness" last year, Hiatte said, it was a priority before then and continues to be so.

"It becomes a part of employees' work habits," he said. "Once you learn how to operate a train fuel efficiently, that becomes how you operate it."

-By Bob Sechler, Dow Jones Newswires; 512-394-0285; bob.sechler@dowjones.com