Rock-solid fuel economy rules

Fuel is one of the largest variable costs for a truck fleet. While no trucking operation can control the cost of fuel, there are tried-and-true ways to control the amount or rate of fuel consumption.

Cummins has compiled what it terms the “rock-solid fuel economy rules” for truck fleets:

Every 2% reduction in aerodynamic drag results in approximately 1% improvement in fuel economy.

  • Above 55 mph, each 1 mph increase in vehicle speed decreases fuel economy by 0.1 mpg.
  • Worn tires provide better fuel economy than new tires, up to 7% better fuel economy.
  • Used lug drive tires can improve fuel economy up to 0.4 mpg over new lug tires.
  • Ribbed tires on the drive axles provide 2–4% better fuel economy than lugged tires.
  • Every 10 psi that a truck’s tires are underinflated reduces fuel economy by 1%.
  • The break-in period for tires is between 35,000 and 50,000 mi.
  • Tires make the biggest difference in mpg below around 50 mph; aerodynamics is the most important factor over 50 mph.
  • The most efficient drivers get about 30% better fuel economy than the least efficient drivers.
  • Idle time is costly. Every hour of idle time in a long-haul operation can decrease fuel efficiency by 1%.


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