The Fuel Efficiency Myth Buster Guide
Fuel economy advice is everywhere—from your neighbor’s garage wisdom to viral TikToks claiming to double your mileage. But how much of it actually holds up under scrutiny? With gas prices as volatile as ever, it’s time to separate fact from fiction and get real about what improves (or doesn’t improve) fuel efficiency.
Here’s a myth-busting guide based on data from the U.S. Department of Energy to help you make informed decisions that genuinely save gas and money.
Myth #1: Letting Your Engine Warm Up Saves Fuel
Busted: This is a leftover habit from the carburetor days. Modern fuel-injected engines do not need to idle for several minutes before driving. In fact, idling for more than 10 seconds wastes more fuel than restarting your engine. The best way to warm up your vehicle is to start driving gently.
Myth #2: Premium Gas Improves Fuel Economy in Any Vehicle
Busted: Unless your owner’s manual specifies premium fuel, using it won’t improve your car’s performance or fuel economy. Higher octane is designed for engines that need it, not for everyday driving. Using premium in a regular engine just costs more without providing any benefit.
Myth #3: Manual Transmissions Always Get Better MPG
Busted: While this used to be true, today’s automatic transmissions—especially newer models with continuously variable transmissions (CVTs)—are often more fuel-efficient than manual versions. It depends on the specific vehicle and how it’s driven.
Myth #4: Filling Up in the Morning Gets You More Gas
Busted: The idea here is that cooler morning temperatures make fuel denser, giving you more for your money. In reality, gas station underground tanks are insulated, and temperature fluctuations at the nozzle are negligible. Timing your fill-ups for price, not temperature, is far more effective.
Myth #5: Using the A/C Wastes More Gas Than Rolling Down the Windows
Partly True: At low speeds, rolling down the windows is more efficient than running the A/C. However, at highway speeds, open windows increase aerodynamic drag more than using moderate A/C. It’s about context—use A/C smartly and avoid blasting it unless necessary.
Myth #6: You Should Replace Your Air Filter to Improve MPG
Partly True: In older cars, yes. In modern fuel-injected vehicles, a dirty air filter doesn’t significantly affect fuel economy, though it can impact acceleration. Regular maintenance is still important, but this particular fix may not move the MPG needle much.
Myth #7: Cruise Control Wastes Fuel
Busted: On flat terrain, cruise control actually helps maintain a steady speed, improving fuel efficiency. On hilly roads, it can be less efficient because the system may accelerate unnecessarily to maintain speed. Use it smartly, especially on highways.
Myth #8: Fuel Additives Boost Mileage
Busted: Most off-the-shelf fuel additives make bold claims but offer limited, if any, real-world benefits. Unless your mechanic recommends a specific product for a particular issue, additives are more marketing than miracle.
Myth #9: Driving Slower Always Saves Gas
Partly True: While excessive speeding kills fuel economy, driving too slowly on highways can also reduce efficiency. Most vehicles hit their peak fuel economy between 50 and 65 mph. Staying in this range is ideal.
Fact: Maintenance, Driving Habits, and Smart Planning Matter Most
What actually boosts fuel economy? Keeping your tires inflated, using recommended motor oil, planning routes efficiently, and avoiding aggressive driving. These tried-and-true habits are what really move the needle—not magic tricks or viral myths.
