Dollars & Sense
Don't Kill Your Fuel Economy!
By Jeff Jensen, Editor
Nov 30, 2007 - 6:09:00 AM

For many trucking and expedited owner-operators, the difference between success and failure can be measured in miles per gallon.

An American Trucking Associations study estimates that in the United States about 1,000 carriers with five or more trucks go under with every 10-cent rise in the national average retail price of diesel.

According to the Technology and Maintenance Council's book on fuel economy, the biggest potential fuel-saving device in a truck is the driver.  The experts say a substantial fuel economy improvement is possible with savvy operating practices and judicious use of today’s technology.

Those same authorities tell us that an experienced driver who employs fuel-saving techniques can be 35% more fuel efficient than an inexperienced or untrained driver.

Technology and equipment ain't all of it
Truck aerodynamics, engine type, gear ratios, tire size/type and other spec items are all important to the quest for fuel economy, but programming your personal driving habits towards saving fuel is the most essential part of the equation.

If your primary focus (along with safety, of course) is centered upon squeezing every mile from every drop of fuel, you will develop those habits that will keep a greater portion of your money in your pocket and not the fuel tank. 

What the fuel-misers tell us about those fuel-saving habits:

Cut your speed
You'll use 5% to 8% more fuel for every 5-mph increase in road speed. In other words, if you slow your cruising speed from 75 to 65 mph, you could save 10% to 16% in fuel.

You should always take the speed limit as your target speed.  Now, most drivers don't like running at 55 mph, but let's look at this tractor-trailer scenario.  If your big truck averages 6 mpg at 65 and 7 mpg at 55, driving that 10 mph faster over a 120,000-mile distance will cost you more than $5,000 at today's fuel prices.

Starting out
A modern diesel (and even most old ones) need only a few minutes to warm up in the morning, and the temperature will come up as you leave your overnight parking spot and head for the highway.  Get moving shortly after cranking over the engine, and shut it off as soon as you're parked. 

Except in extreme temperatures (hot or cold), limit warm ups and cool downs to five minutes.

Progressive shifting
When starting out, upshift (short shift) at low rpm's in low-range gears, gradually increasing rpm's as road speed increases. For example, if the engine idles at 600 rpm, gently engage the clutch, let the truck start moving, then apply a little pedal.  Shift to 2nd at 1,000, to 3rd at 1,100, to 4th at 1,200 and so on.

This is also called progressive shifting, and can be done because you don't need the horsepower produced at higher rpm's until the truck approaches highway speeds, and it's true no matter what kind of truck you drive.  Never rev the engine to its top governed speed (especially if it's a 2,100-rpm engine) unless you're climbing uphill and need a bit of extra time to upshift.

For those with automatic transmissions, disregard the above.

Gravity and momentum
Another part of speed management is maintaining the truck's momentum.  Use the road to help.  Gain some extra momentum on downhills to help you slingshot the next grade.

Plan ahead on upgrades. Avoid storming a hill at the highest speed possible, and instead estimate the final gear you'll need to top it.  Get into that gear early and stay there, and feed the engine only the fuel it needs to sustain a speed in that gear.

Then, ease off the gas as you approach the hill's crest. Upshift just before you reach the top, then stay off the gas and let the truck's momentum carry you over.
  
Let gravity do the work.  As you begin rolling downhill, leave the accelerator alone.  Gravity will increase the truck's speed unless it's a very shallow grade or you're heading into a strong head wind; in those cases, use only the minimum amount of power to return to a sensible cruising speed. Skip-shift as speed climbs, but let revs go up if you'll need the engine brake to control your downhill speed.

Cruisin'
The smart driver also relies on his cruise control, knowing that mechanism is better at saving fuel than he is.  It helps a driver stay relaxed and prevents speeds from creeping up.  Many engines are set up to deliver more power and torque when the cruise is engaged, so turn it on and use it. 

Don't idle.     
Turn off the engine whenever you can, such as long red lights, waiting on traffic tieups to clear and while waiting at the docks.

How often have you pulled into a truckstop with the temperatures in the 60's and all the trucks in the lot are idling?  Are they running their heaters or air conditioning?  As the price of fuel continues its march skyward, more owner-operators will be turning the key off.

Ideally, we would all have APU's or auxiliary heating/cooling in our trucks, but if you can't swing the expense right now, you can still lower your fuel cost.     

In cool weather, try to avoid idling the engine overnight by using warm blankets or a sleeping bag; you'd be surprised how comfortable you can stay once you get used to it.

In moderate weather, leave the windows open a little for ventilation and if you can, park upwind of other trucks to avoid their exhaust fumes. In hot weather, idle to run the air conditionerbut only when you really need to.

Now, take all that money you saved on fuel and buy yourself something, you deserve it!