Reducing highway speed by five miles per hour can cut fuel use and greenhouse gas emissions by over seven

percent while extending the life of a truck’s engine, tires and brakes. A long-haul truck with 90 percent highway

operation that reduces its top speed from 70 to 65 miles per hour could cut its annual fuel bill by $1,450 while

eliminating nearly ten metric tons of greenhouse gas reductions.

What is the challenge?

A typical combination truck spends 65 percent or

more of its operating time at highway speeds. Linehaul trucks spend even more time on highways. The

impact of speed on fuel economy depends upon

many factors including vehicle aerodynamics, engine

speed and operating conditions. As a general rule of

thumb, increasing speed by one mile per hour

reduces fuel economy by about 0.1 miles per gallon.

For a truck with poor aerodynamics, the fuel penalty

may be nearly twice as great. Higher speed also

leads to higher maintenance costs by increasing

wear on the engine, tires and brakes.

What is the solution?

Speed management is an easy and effective way to

save fuel, reduce emissions, and prevent excess

wear. A trucking firm or driver can adopt a speed

policy at little or no cost. The most successful speed

management policies combine technology (e.g.,

speed settings on electronic engine controls) with

driver training and incentive programs to encourage

drivers to maintain speed limits. Most new truck

engines are electronically controlled so the cost of

changing maximum speed settings on these engines

is negligible.

The results are in . . . 

Although fuel savings may vary by vehicle and speed

range, a national trucking association estimates that

a combination truck driving 55 miles per hour uses up

to 20 percent less fuel than a similar truck driving 65

miles per hour. Other analyses indicate that reducing

the maximum speed of a typical long-haul truck from

70 miles per hour to 65 miles per hour could save

about $1,450 in annual fuel costs. Reducing the

maximum speed to 60 miles per hour could save an

additional $1,850, bringing the estimated annual

savings to $3,300.

Reducing speed can cut truck maintenance costs

and reduce the frequency of maintenance work. The

time between engine overhauls, for example, is

directly related to fuel use. Holding maximum speeds

at 60 rather than 70 miles per hour reduces engine

wear and extends time between engine rebuilds,

saving hundreds of dollars per truck each year while

keeping revenue-earning equipment on the road.

Fleets that adopt speed policies report added savings

due to fewer brake replacements and other service

work.

Reducing highway speed does increase travel time.

Assuming ideal conditions, a trucker driving 60 miles

per hour instead of 65 miles per hour could spend

about eight percent longer on the road. Of course,

the time difference may be less, depending upon

road conditions, weather, traffic congestion, and road

construction. If a trucking company pays its drivers

by the mile or by the load rather than by the hour,

reducing speed should not increase labor costs. It

could reduce the productivity of trucking operations

since slower trucks may carry fewer loads. However,

the benefits of lower fuel and maintenance costs

combined with less frequent out-of-service work and

driver safety considerations may well outweigh any

costs associated with increased delivery time. 

Next steps

A trucking company interested in saving fuel and

lowering the cost and frequency of its equipment

maintenance should consider adopting a speed

management policy, particularly if its trucks spend

considerable time on highways. A number of wellmanaged truck fleets have programs in place to

reduce highway speed and promote safe driving by

using driver training, incentive programs and

electronic engine controls. A trucking fleet interested

in following these examples may learn more by

reading articles and fleet profiles in truck industry

publications. When purchasing new vehicles, a

trucking company may also consider specifying

equipment designed to optimize truck performance at

lower maximum speeds. Trucking companies and

drivers interested in learning more about the effects

of speed on fuel economy may contact truck and

equipment manufacturers or their state and national

trucking associations.