# Tailgate Down Doesn't Save Fuel. Physics Explains Why.
The tailgate-down myth persists among truck owners hunting fuel savings. Lowering your tailgate does not reduce aerodynamic drag. It increases it.
Air flowing over a truck bed creates a vortex at the tailgate. When closed, this vortex stays contained. An open tailgate destroys that aerodynamic seal. Wind enters the bed, swirls chaotically, and separates from the truck body. This separation dramatically raises drag coefficients.
Real-world testing confirms the penalty. Trucks lose 5 to 10 percent fuel economy with tailgates down. At current diesel and gasoline prices, this cost outweighs any perceived benefit.
Manufacturers engineer tailgates as load-bearing aerodynamic components. Ford, Chevy, Ram, and Toyota design them closed for optimal efficiency. Modern pickup trucks achieve 20+ mpg partly because engineers seal the truck bed tight.
The efficiency gains come elsewhere. Undercarriage panels, wheel covers, and bumper design matter more. Tire pressure and driving behavior dominate fuel consumption.
Truck owners chasing economy should focus on speed. Dropping from 75 mph to 65 mph saves 15 percent fuel. That beats any tailgate game.