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Four Fuel Economy Myths Debunked

Posted March 15, 2019


These days it can seem like there are as many tips for improving your vehicle’s fuel economy as there are performance additives in fuel. Many of these tips apply only to older engines and not to modern fuel injection systems. So, it’s important to be able to sort fact from fiction when it comes to getting more miles per gallon (MPG) from your company vehicles.

Fuel is a significant business expense whether your business runs on a single vehicle or a local fleet. Most vehicle owners are well aware of how regular tune ups, better driving practices, and good tire and wheel alignment can help them get the most out of a gallon of fuel. But it’s also important not to sweat the small stuff. Please keep reading for information on a few of the most common fuel economy myths debunked, informed by Consumer Reports (CR) and the Clean Fleet Report. 


Myth 1: Running on Empty Will Hurt Your Car or Truck’s Engine

Some drivers worry that running on empty can pull debris into the engine from the bottom of the fuel tank. According to CR, running on empty should not be a big concern “as the fuel pump always pulls gas from the bottom of the tank, even when it’s full. If there were a debris problem, it would surface long before the fuel gets low.”

In modern vehicles there’s usually a fuel filter in the gas tank as well as one nearer to the engine.  So, it is unlikely that debris is getting through.


Myth 2: Changing Your Air Filter Will Improve Your Mileage

CR attests that changing your air filter probably won’t improve fuel economy with modern cars. The Clean Fleet Report points out that the engine computer and air flow sensors in newer vehicles carefully manage the fuel/air mix in the engine, ensuring that you can achieve maximum fuel economy regardless of air quality.

Replacing a dirty air filter will, however, improve performance. If your air filter is filthy, less air is getting inside the engine during hard acceleration. This means your vehicle could take longer to speed up.


Myth 3: Warm Up Your Car Before Driving

As CR points out, “that adage held in the days of carburetors, but it isn’t the case with modern fuel-injected electronically controlled drivetrains. Engines are most efficient when they’re at regular operating temperature, and the fastest way to reach that point is to drive right after starting your car.” The advanced synthetic oils of today also remove the need for warming up an engine before driving.


Myth 4: Refuel When the Air is Cool

If you’re someone who refuels early in the morning when the weather is at its coolest in the hopes of getting a bit more fuel into your engine at the pump, you can stop stressing. CR states that “any extra [fuel] gained by refueling when temperatures are cooler will be negligible and not make a practical difference.”

Why is this? One theory is that cooler gasoline is denser and hence can provide more bang for your buck. “But most stations store the gasoline underground, so its temperature changes very little, if at all, during a 24-hour stretch.”

If you’ve been waking up extra early in these cold winter months to warm up your engine and refuel first thing in the morning, perhaps you can now hit that snooze button at least once. For accurate tips on how to truly maximize your fuel economy, check out this recent WEX Fleet Dispatch blog, “How to Improve Your Vehicle’s Fuel Economy.”


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