The aerodynamic differences between two tractors close-coupled to a Dry Van can amount to 0.55 mpg or a 9% penalty.

The tractor-trailer gap for a high cube trailer (Dry Van, Reefer) is another factor affecting aerodynamics. A 6' gap can represent a 7.5% penalty or 0.45 mpg. Testing by a major OEM has shown that for every 10 inches of trailer gap, the fuel mileage changes 1%.

The tractor-trailer combination can represent up to 1.8 mpg or a 30% difference in fuel mileage penalty. This is based on a comparison between an aerodynamic tractor-trailer (Dry Van) with an 18" gap and a Car Hauler, both with 80,000 lbs Gross Combination Weight (GCW).

As you can see, the tractor-trailer aerodynamic package is another very large contributor to a vehicle fuel mileage performance. It is ironic that a tractor with poor aerodynamics can generate a larger trade-in residual value. A business decision should be made to weigh the additional fuel cost against the higher trade-in value of the tractor.