Ordering an aero-model truck is generally the first thing you can do, specs-wise, to better your chances of posting good mpg numbers. Tests show air resistance is a rig’s second-greatest impediment to movement; only weight slows the truck down more. Gross weight is determined much more by the cargo than the vehicle itself, so you have little control over weight unless you can haul only “balloon” freight. But you can pick a truck with good aerodynamics, which smooth the flow of air over, under and around the rig.

There are lots of arguments for picking a “large car”-the likes of which Pete staked its image on-with its long, flat nose and all sorts of chromed appliances hanging off the hood and roof. Style is what appeals to most folks: a long-nose conventional just looks like a truck, or at least what trucks looked like in the old days. The mystique of a large car makes it easy to sell, and it usually brings more money than an aero-type truck.

But even a large car will usually have an air deflector on the roof. And choosing an aero model can save up to 4 cents per mile in fuel, according to one truck manufacturer. If you run large cars to attract and retain good drivers, you might offer to share fuel savings with them if they agree to drive an aero model instead. All other things being equal, lots of drivers would change jobs to get a 2- to 4-cent-a-mile raise, let alone the type of truck they drive.

Aero-style trucks like Pete’s 387, Kenworth’s T2000, Volvo’s VN, and Freightliner’s Century Class usually come with all the air deflectors included for your trucking application. If you pull a van or reefer, like most truckers, the most important deflector is the one on the cab’s roof. It moves air up and over the roof of the trailer. Without it, air blasts straight into the trailer’s nose, which is like pushing a barn door. It creates considerable drag and costs plenty of fuel to overcome.

A full cab roof fairing-one that matches the height of the trailer-will save up to 15% compared to running with nothing at all. If your tractor has a raised-roof sleeper, chances are it’s a little shorter than the trailer’s roof, so you’d need a small fairing to kick the air completely up. Without it, you’d lose 4% to 10% of the benefits of a full roof fairing.

If you pull a low-height trailer, like a tanker, grain hauler, or flatbed, a full-height deflector would probably add resistance. You’d do better with a flat-roof or mid-roof sleeper that better matches your trailer. Because of this (and also to reduce purchase prices) aero tractors can be ordered with varying sleeper types (or with no sleeper at all). Work with your sales person to pick the one that’s right for you and your operation.

Other deflectors usually come as a package on an aero tractor. These include cab extenders, which plug some of the gap between tractor and trailer; side skirts, which cover the fuel tanks and battery box and smooth out the profile of the steps; and an air-dam front bumper. If you put any of these on a non-aero tractor, you might pick up 1% to 3% in fuel economy.

Medium-duty trucks often run in cities where stop-and-go traffic pulls down average road speed and reduces the benefits of aerodynamics. That’s why few city trucks have full fairing packages or any fairings at all, but most have smooth styling to ease air flow. And the van boxes mounted on many mid-range trucks have rounded roof edges to reduce wind resistance.

Any truck owner whose rig spends a lot of time on freeways where cruising speeds are high would save fuel if the truck is fitted with a supplemental fairing on its nose or on the cab’s roof.

And that’s not blowin’ smoke.