5 Common Myths About Fuel Efficiency
Most people are familiar with the tried-and-true habits that can help save fuel. Drive smoothly. Keep tires properly inflated. Don’t speed. All of these are well-known and proven ways to improve fuel efficiency.
But what about this one: Coasting downhill in neutral saves fuel.
Despite what some drivers believe, that’s a myth. Not only can coasting downhill be dangerous — and illegal in more than 40 states — modern vehicles are designed to use fuel more efficiently when they remain in gear even when the accelerator isn’t being pressed. So, keeping the vehicle in gear can actually use less fuel than coasting in neutral. But for whatever reason, this is a fleet fuel economy myth that many drivers mistakenly continue to believe.
Fuel myths are more common than you might think. While some are harmless misconceptions, others aren’t, and they can actually increase your fuel consumption and operating costs.
For fleets, these costs can add up quickly. Fuel is one of the largest operating expenses, so even small improvements in fuel economy can lead to significant savings. That’s why separating fuel economy fact from fiction is critical to efficient fleet operation and fuel management practices.
To that end, let’s look at five of the most common fleet fuel economy myths — and the truth behind them — so you can help your drivers stay safe, operate more efficiently, and get the most from every gallon of fuel.
MYTH: A Dirty Air Filter Reduces Gas Mileage
This myth is rooted in older vehicle technology. Years ago, this was often true because older engines relied on carburetors and were more sensitive to airflow restrictions.
Modern vehicles are different. Fuel-injected engines use sensors to continuously adjust the air-fuel ratio. As a result, a relatively dirty air filter has little effect on fuel economy.
But that doesn’t mean ignoring the manufacturer’s recommended maintenance schedule. A severely clogged filter can reduce engine performance, affect acceleration, increase emissions, and place additional strain on the engine.
For fleets, the takeaway is simple: replace air filters according to the manufacturer’s recommended maintenance schedule, but don’t expect filter replacements alone to produce significant fuel savings.
MYTH: Keeping the Fuel Tank at Least Half Full Prevents Fuel Evaporation Inside the Tank
Logically, this makes sense. Less empty space in the tank means less opportunity for fuel to evaporate. This may have been true decades ago, but modern vehicles are equipped with sealed evaporative emissions systems designed to capture and control fuel vapors. Rather than escaping into the air, these vapors are stored and later routed back into the engine to be burned.
While keeping the tank at least half full won’t improve fleet fuel economy, it can be a good practice for your drivers to follow — particularly when severe weather events occur and fuel availability may be limited, your fleet operates in remote areas, and when drivers are stranded and need to keep the engine running. Learn more about how winter weather affects fuel economy here.
MYTH: It Takes More Fuel to Start a Vehicle Than It Does Allowing It to Idle
This myth has been around for years. But the reality is that excessive idling is a big-time fuel waster. Depending on vehicle type and engine size, idling for just 10 minutes can consume approximately 0.03 to 0.08 gallons of fuel.
Modern engines are designed to start efficiently. While shutting off the engine and restarting does require a small amount of fuel, restarting uses less fuel than allowing the engine to idle for an extended period. A general rule of thumb for your drivers: if you plan on idling longer than 30 seconds, shutting off the engine and restarting is more fuel-efficient than idling.
Idling doesn’t just waste fuel — it increases engine wear, contributes to emissions, and increases operating costs. For fleets, reducing idle time is one of the simplest and most effective ways to improve fuel economy and lower fuel costs.
MYTH: Warming Up Vehicles Improves Fleet Fuel Economy
This myth dates back to the 1980s when carbureted engines often required extended warm-up time before driving.
Modern fuel-injected engines are designed differently. They automatically adjust the air-fuel mixture needed for efficient operation. Unlike older carbureted engines, they don’t require extended warm-up periods before driving.
Typically, driving the vehicle is the quickest way to warm up the engine. Just make sure you allow the engine a brief moment to circulate oil — especially in very cold conditions. Gentle driving is more effective than sitting and idling. There’s less wasted fuel, fewer emissions, and a faster warm-up.
MYTH: Older Vehicles Automatically Get Poor Fleet Fuel Economy
Many people assume that fuel economy declines dramatically as a vehicle gets older. While wear and tear can affect performance over time, age alone does not mean poorer fuel economy.
According to the EPA, a vehicle that’s properly maintained will retain its efficiency for many years — even a vehicle that’s 10 to 15 years old will experience a slight decrease in fuel economy if properly maintained.
There are several reasons you may want to retire a vehicle, including maintenance costs, safety standards, resale value, asnd reliability issues — just don’t assume a newer vehicle with the same engine type will automatically deliver better fuel economy.
Fuel Wise: Separating Fact from Fiction
Fleet fuel economy myths have a way of sticking around long after vehicle technology has changed. By helping your drivers understand what actually improves fuel economy — and what doesn’t — you can reduce fuel waste, lower emissions, and lower operating costs. Improving fuel economy doesn’t always require major changes. Sometimes it’s simply separating fuel economy fact from fiction.
Interested in learning other factors that can impact fleet fuel economy? Read our comprehensive guide to get a closer look.