Dollars & Sense

Pocket The Savings

By Jeff Jensen, Editor
Posted Aug 10th 2007 3:21AM

Achieving better fuel economy is not found in any one practice, but rather a series of small practices and techniques. To list all of the experts' fuel economy suggestions would literally take a book; in fact, one has been written - the Technology and Maintenance Council's Recommended Practice 1111. RP 1111 is among the contents of TMC's huge, two-volume Recommended Maintenance Practices Manual.

Your fuel economy counselor
Given the special-use nature of the expedited straight truck, one of your best sources to spec for fuel economy will be your dealer's expedited truck specialist. These salespeople have years of experience in helping expedited owner-operators to enhance their equipment bottom line and they know what works. Pay heed to their suggestions and pocket the savings.

The most important component is you
Lots of things can help, but the biggest single item is the person behind the wheel. You can obtain impressive mile-per-gallon figures if your truck is set up with good basic specifications, but there's one key component in the fuel savings equation: you, the driver.

Your driving techniques and habits can have as much or more impact than the specs. Poor driving habits will negate most of the gains from fuel-saving technology or devices.

One expert contends that any driver would instantly improve his fuel economy if he taped an egg to the bottom of his right foot. The egg would require the driver to acquire a feather touch on the go pedal and the brake, thus improving economy.

Watch your speed
Road speed can be a fuel waster. Even if it's geared for high speeds, the faster you drive, the more fuel the truck will use.

An old formula says that you lose 0.1 mpg for every 1 mph over 55. Even with today's improved aerodynamics, you'll use 5% to 8% more fuel for every 5-mph increase in road speed. Or, if you slow your cruising speed from 75 to 65 mph, you can realize a 10%-16% savings in fuel.

Reduce Engine Idling
With the ever-escalating price of fuel along with the anti-idling legislation across the nation, it's become difficult to justify idling the truck's engine unless it's absolutely necessary for heat or air conditioning.

In a perfect world, every truck would be APU- or diesel-fired heater equipped, but you can still save fuel simply by changing a few habits. If you could cut your idling time from 50% of all engine hours to 10%, you'll save about 7% in mpg.

Try shutting down the engine during:
-Overnight parking (if temperatures allow)
-Rest stops
-Meal breaks
-Railroad crossings
-Highway traffic stoppages

Spec'ing the equipment
The experts tell us that selecting an aerodynamic truck model is possibly the most important component to consider when spec'ing a truck for fuel economy. Studies have shown that air resistance is a truck's second greatest hindrance to movement; only weight provides greater resistance.

If you select a truck with good "aero" characteristics, which will smooth the flow of air around the unit, your fuel will be used to carry the weight of the truck and its load, not fighting air resistance.

Medium-duty pick up and delivery trucks have historically run in cities where stop-and-go traffic pulls down average road speed and reduces the benefits of aerodynamics. That's why few have full fairing packages, or any fairings at all.

However, with the advent of expedited trucking and its wide use of medium-duty platforms, these trucks now enjoy more aerodynamic styling. The van bodies mounted on many midrange expediters have rounded leading edges to reduce wind resistance and today's sleepers are designed with aerodynamics in mind.

Any truck that spends a lot of time on freeways where cruising speeds are high would experience significant fuel savings if fitted with the wind-cheating body fairings available.

Gear ratios
Gear ratios in the transmission and rear axle(s), along with the tire/wheel size, determine how fast the engine will spin at a given road speed. Each must be chosen with the other in mind. Tire sizes can be changed fairly easily, but swapping gears is expensive and is not always practical. So get the specs right the first time, or look at a truck's overall gearing carefully to be sure it suits your operation.

Rolling resistance
Tire tread type greatly affects fuel economy because it helps determine rolling resistance. The least resistance is offered by rib-style tires, and most trucking fleets try to put these at all wheel positions, weather permitting.

Switching the drive axles to lug-type tires in winter improves traction but adds resistance, and costs 2 to 4% in fuel economy. Installing "shallow rib" tires on a trailer can save 6 to 14% in fuel compared to a trailer with regular ribs.

Components
-A "tag tandem," where a single drive axle is paired with a non-powered tag or pusher axle, can save 2% to 3% over a "live" twin-screw tandem.

-A bug deflector can rob you of as much as 1.5% in fuel because it disrupts the air flow over the hood.

-Research has shown that a broken-in truck encounters fewer losses due to the various parts "settling in" and the brakes dragging less. After about 10,000 miles of break-in, a truck should use 2%-5% less fuel than a brand-new one.

-On/off fan drives can be fuel savers by turning off the power-robbing fan, depending on the engine's cooling requirements. Savings can range from 0.5% to 18%.

-Synthetic gear lubricant in axles and transmission can save up to 0.5% in summer and 2% in winter.

Other factors affecting fuel economy

Weather
Winter operations consume 8% to 12% more fuel than summer driving because rain, ice, snow and cold temps create rolling resistance and stiffen gear lube; and the engine's likely to idle more.

Terrain
A flat route instead of one that includes steep hills and mountains can save 4% to 18% in fuel.

Interstates
Fewer stops and gentler grades and curves save time and 4% to 11% in fuel compared to two-lane roads.

City driving
The stop-and-go of city driving can cost 45% to 165% more fuel than if you take the bypass.