Allison Transmission, Inc. has announced that recent test results show fully automatic Allison transmissions, along with a vehicle spec that is appropriate for the particular duty cycle, can provide superior fuel efficiency and optimum fuel economy.


According to Lou Gilbert, director, North American Marketing, Allison Transmission, "A truck's duty cycle can be broken into four components: acceleration, cruise speeds, deceleration and idle. Of these, acceleration and cruising are the main factors impacting fuel consumption."

During acceleration, an Allison Automatic provides smooth, seamless full-power shifts to put engine power to the ground in the most fuel-efficient way. Manual and automated manual transmissions interrupt engine power every time a shift is made. According to Gilbert, recent data log analysis of two North American P&D fleets shows an average of over 600 upshifts during an eight-hour timeframe, Allison officials say.

"Any interruption in engine power during a shift creates powertrain inefficiencies, loss of vehicle energy, lower average speeds and, ultimately, less work is accomplished with the fuel consumed," according to Steve Spurlin, executive director, 3000/4000 Series Transmissions and Application Engineering, Allison Transmission. Adds Gilbert, "With full-power shifts, fleet managers will recognize higher average speeds versus manual or automated manual transmissions. Higher average speeds over a day mean the Allison Automatic accomplishes more work for the fuel utilized. So it is more fuel efficient."

This is in line with how the U.S. Environmental Protection Agency (EPA), as part of its SmartWay Program, is formulating a test protocol proposal to measure the fuel efficiency of medium- and heavy duty commercial vehicles for the first time. According to industry reports, the EPA's fuel consumption metric for this test would be fuel consumed per amount of work performed, which is not the same thing as simply miles-per-gallon (MPG).