Gas Mileage Myths - NBC 7 San Diego

Consumer Bob helps to save you money and time

Gas Mileage Myths



    Three ways La Jolla UTC delivers on what employees really want
    Getty Images

    The higher the gas prices, the more crazy ideas on how you can get more miles from a drop of fuel.

    There are myths and then there are solid facts that will help you get better mileage.

    What about keeping your car in idle instead of stopping and restarting? 

    "If it's a fuel injected engine, it's probably cheaper to shut if off after about 35 or 40 seconds,” said Charles Langley with the consumer group UCAN.

    Today's cars just don't use that much gas to get started, so don't let the car sit in idle thinking it will cost more to start it up again.

    What about filling your car with gas? Is it worth buying gas in the morning when it's cold?

    “There is something to the theory of that because fuel is denser, meaning there are more molecules per volume when it's colder.  But in a tank that holds 20 gallons, you're not going to notice a difference,” said mechanic Tim Kotter.

    And once you buy the gas, what about all those things you can add to your tank that promise to give you better mileage?

    “Most of the fuel additives out there are highly questionable and probably not worth the money,” said Langley.

    “The number one thing I think is proper tire inflation,” Kotter.

    Most experts agree that checking your car's air pressure is one of the most important things you can do to increase gas mileage. It may not look it, but you could easily be driving right now on under inflated tires.

    So how much tire pressure do you use?

    Don't go by the information that's printed on the tire itself. Instead go by your car's owner manual or you'll find a sticker on your doorframe.

    “Some people tend to want to over inflate in this situation. The problem with that is the trade off because over inflation will make the tire wear out prematurely,” said Kotter.

    A properly tuned car is a plus.

    Using your air conditioner will also cut down on your mileage, but opening your windows can do the same thing.

    “The windows open creates drag on the car and slows it down. It turns it into a big sail,” said Kotter.

    NBC San Diego and UCAN are joining together to hand out "Guzzler Buster" -- a free publication offering money saving tips.