Initial results of a fuel economy study by truck leasing firm PHH First Fleet, Ft. Lauderdale, FL, suggest that truck specs—especially engine size and gear ratio—impact vehicle fuel efficiency more than most people think.
“What surprises me is the depth to which spec’ing choices can influence fuel economy,” Hal Booth, senior vp at PHH First Fleet, told FleetOwner. “In the past, we’d focused more on how engine idle time, driver behavior, and vehicle speed affected fuel efficiency. Now we’re finding how the truck is spec’d from the outset impacts a fleet’s ability to get the best fuel economy possible.”
“Specs really determine how you harmonize the truck and driver to get the best fuel economy possible,” added Alex Popov, PHH First Fleet’s vp-fleet services. “The information we’re generating through this study by way of telematics is what’s going to enable a fleet manager to put together the right truck for their specific application to maximize fuel efficiency.”
PHH First Fleet is using data gained via onboard telematics installed on customer vehicles to map out what affects vehicle fuel economy. At the 10-month mark, results support the following hypothesis: While horsepower and torque are directly proportional to one another, if the output torque range or engine load percentage is maintained at a significantly lower percentage rate and the horsepower and rpms are over-spec’d, fuel economy will increase.
“Gear ratios also impact engine speed, acceleration, fuel consumption and performance,” Ezel ‘C.J.’ Minnet Baltali, the company’s fleet services application engineer, told FleetOwner. Baltali overseeing the fuel study.
“A higher gear ratio may increase performance while driving in lower gears, but it lowers fuel economy,” he added. “That’s one example of how the data we’re getting is going to definitely improve our ability to develop the right specs so fleets can better hit the ‘sweet spot’ in terms of adequate engine power and best possible fuel economy.”
In the next phase of the study, some of the trucks will become control vehicles in which no variables are changed, while others will undergo calculated adjustments to engine ratings and axle ratios to equate them with better performing trucks in other fleets, Baltali said. Participating fleets are largely from the grocery, manufacturing, fuel and retail distribution markets. All are private fleets, and all are customers of PHH.
PHH First Fleet highlighted two fleets that operated their trucks with slightly different engine specs in similar terrains and climate conditions. One is based in Northern California, while the other operates in the Northeast.
The California fleet, equipped with 455 hp. @ 1800 rpm and a 2.79 gear ratio (2.79), and operating at a lower percentage of the torque range, is getting 6.5 mpg. The fleet operating in the Northeast, which has variable horsepower (435 to 475 hp @ 1800 rpm) and a 3.9 gear ratio, is averaging only 5 mpg.
Those numbers are extremely significant, noted Michael Lewis, president and gm for PHH First Fleet. Based on current fuel prices, a 100-truck fleet that increases fuel economy by just 0.1 mpg per vehicle can generate savings of $65,000 annually. He pointed out that FirstFleet’s objective is to help customers improve fuel economy by 0.3 mpg, saving them $200,000 a year or $2,000 per year, per tractor.
“[We’re] searching for answers beyond the obvious, like idling time and road speed, that private truck fleets have been successful in finding on their own and resolving,” Lewis said. “The initial findings of our study are pointing to two major factors – engine specs and gear ratio – that companies can control or modify to increase fuel economy. We’ll require further study to verify their efficacy, but we believe [the fuel study data] is going to help us offer new strategies for achieving better fleet fuel economy.”
To view the study, go to www.phhfirstfleet.com/aboutPHHFirstFleet/mediaCenter/articles/phhFirstfleetprelimfuelstudy.html