Peterbilt said it "harvested" a lot of the aerodynamic benefits achieved during its work with the Dept, of Energy's Supertruck program and applied them to its Model 579 EPIQ spec. Peterbilt's Supertruck tractor is seen here on the left, next to the most recent iteration of its Model 579 EPIQ package (at right).
Frank Schneck, Peterbilt's division engineering manager, provided a detailed walkaround of the latest version of the OEM's Model 579 EPIQ highway tractor package.
Full side fairings include a cutout for the diesel exhaust fluid (DEF) tank refill port on driver's side of the tractor. Schneck is pointing to roughly where Peterbilt can include such a "cutout" for the diesel fuel tank, though the OEM recommeds and "end fill" port for the diesel tanks on both sides of the truck for a better aerodynamic profile.
The Model 579 EPIQ's four starter batteries are tucked into aerdynamically shaped compartment under the drivers-side steps.
The service panel pops opn easily to allow for easy access to the batteries.
Schneck points ot the low front bumper air dam that helps redirect air away from under the chassis to around the sides of the vehicle. However, if the tractor is pulling a trailer without side fairings, it's recommended that such an air dam not be installed.
Tight seals between the headlamp and bumper further help redirect external airflow to the sides of the truck for better aerodynamic performance.
Peterbilt now more widely uses "recirculation shields" within the engine compartment to redirect airflow not required for engine cooling needs out to the side of the vehicle. Previously, Schneck such shields were only used for "high horsepower" engines cranking out over 450 hp. Now they are used below that number; for example, the MX-13 engine powering this particular truck generates just 400 hp.
Wheel hub "close outs" actually help keep and channel air within the wheel well and then out under the vehicle, as side airflow from the wheel end would actually hinder aerodynamic performance. Schneck noted the "close outs" pictured here are made from hard plastic; in the very near future they'll instead be made of rubber.
"Close outs" help seal the gap between the doors and the chassis fairings, again to help "smooth" the airflow along the side of the tractor.
Schneck indicates the spot on this particular truck where the OEM's "Smartair" bunk heating and cooling system is located. Powered by four batteries, it allows drivers to heat and/or cool their bunk space without idling the truck's diesel engine. Peterbilt reduced the size of the diesel fuel tank on the passenger side of the tractor to 90 gallons so it could fit the Smartair system on board.
Schneck points to "kick outs" located at he end of the Model 579 EPIQ's tractor chassis fairings; a "flairing" that helps the airflow around the side of the tractor "jump" more seamlessly to the trailer.
The Model 579 EPIQ includes 18-in. bolt-on side extenders for the sleeper along with an 8-in. rubber extender for a total of 26 inches of tractor-trailer gap coverage. Schneck noted the "ideal" gap space between tractor and trailer is 42 inches. He noted that 26 inches of gap "coverage" provided by the extenders helps block the entrance of crosswinds into the tractor-trailer gap, which would generate turbulence and thus drag, while also providing enough clearance to the trailer when turning.
The back of the cab is kept smooth by routing engine exhaust under the tractor. The A/C condenser is also located at hre bottom of the cab's rear panel to provide more clearance for reefer units as well as to reduce drag.
A view of the Model 579 EPIQ's "ground dump" exhaust stack.
The roof fairing and "bridge" at the top of the Model 579 EPIQ units equipped with sleepers helps airflow along to the top of the tractor "jump" smoothly to the top of dry van and reefer trailers.
Tandem axle wheel covers help keep crosswinds out of the wheel ends, which would create drag. They are clear plastic to provide more visibility of wheel ends and hubs for drivers during their pre-trip inspections.
Finally, tractor tail lights on the Model 579 EPIQ spec no longer "hang" off the rear of the tractor chassis; instead they are embedded directly into the bumper to again reduce drag points on the vehicle.