Fuel Efficiency Myths in Trucking: What Really Works

Myth: Georgia Overdrive Saves Fuel

This is one of the oldest and most dangerous myths in trucking. Georgia overdrive — coasting downhill in neutral — was popularized in the 1970s when mechanical diesel engines did consume fuel during engine braking. Drivers believed that disengaging the drivetrain on downhill stretches would save a meaningful amount of diesel. The term became so widespread that it entered the trucker vocabulary as a standard practice.

The reality in 2026: Modern electronically controlled diesel engines use fuel cut-off during deceleration. When your foot is off the throttle and the truck is in gear going downhill, the engine's fuel injectors stop firing. The engine turns freely using the truck's momentum — zero fuel consumed. In neutral, the engine must idle to stay running, which burns 0.8-1.0 gallons per hour. So georgia overdrive actually uses more fuel than staying in gear.

Myth: Drafting Behind Trucks Saves Significant Fuel

Drafting — following closely behind another truck to reduce aerodynamic drag — does work from a physics standpoint. Wind tunnel testing shows that following at 50 feet reduces drag by 15-20%, and at 100 feet by 5-10%. Some fleets have experimented with platoon technology that electronically links trucks at close following distances. However, for individual drivers, manual drafting is catastrophically dangerous.

At 65 mph, a fully loaded semi needs 300-500 feet to stop. Drafting at 50-100 feet means you have roughly one second of reaction time before impact. If the lead truck hits debris, blows a tire, or brakes hard, the result is a high-speed rear-end collision. The 2-5% fuel savings (roughly $1,500-3,000 per year) is meaningless against the risk of a $500,000 accident or a fatality. No insurance company, fleet manager, or safety director will ever endorse drafting.

Myth: Removing Speed Limiters Saves Fuel

Some drivers believe that speed limiters force inefficient driving patterns — constant acceleration and deceleration around the limited speed. They argue that being free to run at “natural” highway speeds would be more efficient. The data says otherwise. The Department of Energy has documented that aerodynamic drag increases with the square of velocity. Going from 65 to 75 mph increases drag by 33% and fuel consumption by 15-20%.

A truck limited to 65 mph that averages 6.5 mpg will get approximately 5.5 mpg at 75 mph. Over 120,000 miles per year, that is an extra 2,700 gallons of fuel — about $10,800 at $4.00/gallon. Speed limiters are not a fuel penalty; they are a fuel benefit. The discomfort of driving 65 in a 75 zone is real, but the financial math strongly favors the limiter.

What Actually Works: Data-Driven Fuel Savings

The proven fuel-saving techniques are less exciting than miracle additives but far more effective. Progressive shifting saves 5-8%. Maintaining proper tire pressure saves 1-3%. Aerodynamic devices (skirts, tails, gap reducers) save 6-12%. Idle reduction with an APU saves $5,000-9,000 per year. Speed reduction from 68 to 62 mph saves 10-15%. Cruise control on flat terrain saves 3-6%. Route optimization saves 2-5%.