WINNIPEG, Man. – Every O/O’s goal nowadays has to be maximizing the amount of time between visits to a fuel island.

The result is everything from driving habits to spec’ing has been revamped over the past couple of years to allow operators to do just that: Attain their top fuel efficiency possible.

However, it is important not to lose sight of other issues associated with buying fuel and fuel-efficient componentry, or any savings may evaporate quicker than spilled diesel.

Even though your fleet may have an agreement – and a discounted rate – to buy fuel exclusively from one supplier, where you go and how you get there will impact the final price of your go juice.

For example, says Jon Sigurdson, fuel manager with Bison Transport, you can’t underestimate the importance of knowing the International Fuel Tax Agreement (IFTA) refundable tax amounts for each province and state.

“IFTA taxes are calculated based on the amount you drive in a province or state and your overall fuel consumption rate, not on the amount of fuel you purchase in a province or state,” he stresses. “Even if you don’t purchase a single litre of fuel in one province or state, you would still have to pay IFTA taxes in that jurisdiction (based on the miles you run there).”

This means the real cost of diesel fuel is the pump price minus the refundable IFTA tax rate. Thus, in order to determine the least expensive place to buy fuel, you must determine your real cost of diesel fuel. So knowing the IFTA refundable tax rates across North America can go a long way towards reducing your overall fuel cost.

By the same token, fuel efficient spec’ing is no good unless you review the entire truck’s design. You can’t just dump in a new component and expect everything to work properly.

According to Bob Morgillo, warranty/technical support manager with Dana’s Spicer Driveshaft Division, over the last 30 years a dramatic shift has taken place in the spec’ing of drive axles. Today, adds Morgillo, more and more fleet supervisors are ordering new vehicles with increasingly lower numeric axle ratios. That’s because the lower ratios have been proven to favorably impact fuel economy.

“In the ’70s we were seeing ratios ranging in the 4.10 to 4.11 range,” says Morgillo. “In the ’80s the ratios were down to the 3.73 range. Now we’re seeing ratios as low as 3.07 or even lower. Fleet supervisors are obviously convinced that lower ratios equate to better mileage.”

What many of these same supervisors do not know, however, is the fact that lower axle ratios require an unusually high amount of torque during start-up. And that torque is placing an equally high amount of stress on the vehicle’s driveshaft assembly. This stress, in turn, can lead to maintenance complications throughout the entire system.

“Be very careful when specifying your driveshaft,” advises Morgillo. “A size that may have worked just fine (as few as) five years ago … probably won’t do the job as well in today’s trucking environment.”

To remedy the problem, he recommends fleet managers seriously consider spec’ing a driveshaft that is, “larger than those with which they have become accustomed to ordering in the past.”

While Morgillo does admit larger driveshafts may cost more, reducing or even eliminating driveshaft repairs – and costly downtime – over the life of the vehicle will quickly justify the additional expense.