Driving Cat^® Powered Trucks for Maximum Fuel Economy

Rising fuel prices mean that excellent fuel economy is more important than ever to trucking companies. Cat^® engines with ACERT™ Technology are built to deliver outstanding fuel economy and performance, but they need to be driven differently than previous models to achieve their potential, according to Russ Siegel, Test and Demonstration Driver, Caterpillar^® On-Highway Engines.

"The biggest factor in fuel economy—good or bad—is the driver,” said Siegel, who works with Caterpillar customers to help drivers get excellent performance and fuel economy from their Cat engines. “Driving habits have a huge impact on fuel usage. It's critical that companies educate their drivers on fuel-saving driving techniques, as well as specifying their vehicles to achieve the perfect balance of fuel economy and performance."

Russ Siegel, Test and Demonstration Driver

The first step is to specify the vehicle correctly. Gear ratios should be lowered to operate at highway speeds with lower rpm—for example, 3.42, 3.35 or 3.25 instead of the 3.70 or 3.55 that was used in the past. "This lower gear ratio improves fuel economy and enables the driver to work in the preferred torque range for excellent performance," Siegel said.

Drivers also need to be aware that peak torque is around 1,100 to 1,200 rpm, but the horsepower peak isn't until above 1,500 rpm. "It's pretty simple, really—by expanding the torque range, drivers can operate their Cat engines more efficiently and profitably," he said. "Torque starts to fall off around 1,400 rpm—anything above 1,500 delivers a little more horsepower, but eats fuel. Heavy haulers may need to operate that high at times, but should try to avoid it when possible."

To get the most out of a Cat engine when climbing a grade, Siegel recommends bringing the rpm down to 1,100 if the truck can top the hill. But if the driver determines that a down shift will be necessary, doing it around 1,250 or 1,200 rpm keeps up momentum and reduces the amount of down shifts for that hill. "This method will keep you in the 'sweet spot' for all available torque and help you save fuel," he said.

Siegel also advises avoiding downshifting too early when climbing grades. "Cat engines allow you to 'lug the engine,' or operate at 1,000-1,200 rpm, as long as the engine maintains road speed while climbing in the 1,000-1,200 rpm range. In this situation, there is no need to downshift," he said.

ACERT Technology imparts many benefits to the system, according to Siegel. "Operating at lower rpm means less noise in the cab, and the split fuel injection system makes Cat engines with ACERT Technology a more driver-friendly engine," he said. Momentum also plays a role in fuel-efficient driving, Siegel said. Allowing the truck's momentum to take over saves fuel, since the energy through the tires and drivelines is powering the truck.

"Just kick out the cruise control about a mile before your exit and leave it in gear as long as possible—watch how far you can coast for free," he said.

Cat engines with ACERT Technology are designed to deliver excellent fuel economy. Drivers can maximize that benefit by following a few simple guidelines when driving, according to Siegel. "It's important to remember to keep vehicle speed down—fuel economy drops by .10 mpg for every 1 mph over 55. And, you'll maximize fuel economy if you operate in the highest gear possible, so cruise in top gear," he said. "At the same time, keep the engine below 1,500 rpm, downshifting at around 1,100 rpm. Use progressive shifting techniques by upshifting around 1,400-1,500 rpm in the upper gears, and 1,100-1,300 rpm in the lower gears. Remember to use cruise control whenever possible to maintain average speed and good fuel economy."

Staying alert to changing road conditions and adjusting driving technique accordingly is another way to conserve fuel. For example, anticipating slowdowns and stops and coasting in gear will improve fuel economy. In addition, Siegel recommends paying attention to the small details—such as when you're running the fan and how much time you spend idling the truck.

"Don't run the fan while driving, unless you need it. The fan draws horsepower, which reduces fuel economy. Under normal operating conditions, leaving the fan switch in automatic mode will allow it to activate only when needed," he said.

"Idle time is another big fuel waster. Cat engines with ACERT Technology do not require long cooldown periods—if the vehicle will be parked for more than five minutes, shut it down. If idling is needed for heating or cooling, idle between 800-1,000 rpm," Siegel said. "A reduction in idle time from 50 percent to 25 percent can improve fuel economy by as much as four percent."

For a free driver education DVD from Cat, please call 1-800-447-4986, press 4, and request LEVT4042.

For a quick-reference Driver Tips flyer, please click here.

Issue 45 9/26/06
To learn more about Caterpillar On-Highway Engines, please visit:
http://www.cattruckengines.com/.