Is It More Efficient To Drive Your Truck With The Tailgate Open?

Why It Matters

For owners and fleet managers, even a 0.1 mpg gain translates into lower operating costs and reduced emissions, making tailgate position a simple, cost‑free efficiency lever.

Key Takeaways

• Closed tailgate improves fuel economy by ~4% versus open
• Open tailgate raises lift‑induced drag up to 60%
• Mythbusters test saved 1.5 gal, about $6.45 per tank
• Trapped air behind closed gate acts like a tonneau cover

Pulse Analysis

Aerodynamic drag is the primary enemy of fuel efficiency in full‑size pickups. When the tailgate is latched, it creates a sealed cavity that traps high‑pressure air, effectively forming a makeshift tonneau cover. This pocket of air smooths the rear‑ward flow, lowering the vehicle’s coefficient of drag. Even a marginal 0.001 reduction in drag can boost mileage by 0.1 mpg, a figure that adds up over thousands of miles.

Empirical data backs the physics. Consumer Reports measured a 4% fuel‑economy drop when a Ram’s tailgate was opened at 65 mph, while a 2004 study from Canada reported a 60% increase in lift‑related drag for open gates. The popular Mythbusters experiment quantified the real‑world impact: the open‑gate truck ran out of fuel 30 miles sooner, costing roughly $6.45 at current gasoline prices. Though the absolute savings appear modest, they are consistent across different makes and driving conditions, reinforcing the principle that small aerodynamic tweaks can yield cumulative savings.

For commercial fleets and individual owners alike, the takeaway is actionable. Keeping the tailgate up eliminates unnecessary drag without any aftermarket investment, directly improving fuel cost per mile and lowering carbon footprints. When combined with other best practices—steady speeds, proper tire inflation, and regular maintenance—the cumulative effect can be significant. As fuel prices remain volatile, leveraging such low‑effort aerodynamic gains becomes an increasingly valuable component of total cost of ownership strategies.