Following an 18-month study of U.S. truck fleets in a variety of markets, including grocery, manufacturing, fuel, and retail, PHH FirstFleet has discovered new ways to increase fuel efficiency for fleets.

The study found a “sweet spot,” where, when combined with other variables, both fuel efficiency and performance are maximized. The research also found that slightly over-spec’ing engines improves fuel economy, saving approximately 2,000 per tractor, per year (assuming 100,000 miles are driven per year).

In addition to the study results, PHH FirstFleet offers a “Top Five Tip List” to increase fuel efficiency.

1. Increase Engine Torque Ratings

This step decreases time spent in the high output torque ranges, in turn decreasing overrevving. Over-revving often occurs when driving at high output torque ratings, or high RPMs. Overrevving can shorten engine life, leading to lower fuel economy. Driving in a lower RPM range than the engine’s specified parameters can indirectly cause over-revving by requiring increased downshifting.

2. Decrease Gear Ratio

Although higher gear ratios provide extra power in lower gears and may improve overall performance, they cause a loss in fuel economy. A lower gear ratio improves fuel economy, reduces engine wear, increases speed at lower RPMs, and reduces overrevving, according to PHH FirstFleet. Choose the correct rear axle gear ratio for the vehicle’s application and needs.

3. Implement Engine-Specific Parameter Controls

Reduce speed. Driving above 70 mph increases fuel consumption by demanding more than 60% of the engine’s available horsepower. Dropping speed to 55 mph can reduce horsepower demand to 40% and reduce fuel use. At stops, drivers should turn off the engine rather than keep it idling, which uses up to a gallon of fuel per hour. PHH FirstFleet advise progressive shifting. Drivers shifting quickly in lower gears prevents fuel-guzzling overrevving.

4. Spec Auxiliary Power Units (APUs)

These units allow drivers to run applications, such as air conditioning, without running the engine. However, “because APUs carry extra weight, the payload must decrease to meet weight limits,” warns PHH FirstFleet.

5. Improved Chassis

Chassis body innovations have helped decrease wind resistance to reduce required horsepower and increase fuel efficiency. Lighter chassis weight can also contribute to increased fuel economy. However, with “decreased chassis and trailer weight, overall payloads may increase and offset fuel economy improvements,” according to PHH FirstFleet. Low-profile or wide-based tires and wheels can improve fuel economy by 2% to 5%. PHH FirstFleet advises, “Decreased weight and lower rolling resistance are the key contributors to fuel economy improvements.”