Fuel Facts From E3 Spark Plugs

All that "junk in the trunk" is great for your girlfriend, not so much for your car's fuel economy. E3 Spark Plugs' fuel facts help you see just how much gas you're wasting.

We all know a well-maintained vehicle gets better gas mileage than one not so well kept. To get the most out of your car, spark plugs, gas caps, thermostats, O2 sensors, even that rarely used luggage rack and all that junk in your trunk can drag down your fuel efficiency. But exactly how bad is each of these issues for your gas tank and wallet? E3 Spark Plugs has worked a few numbers to put it all in perspective:

  • Each year, 147 million gallons of gas vaporize into the atmosphere – all because of misused or missing gas caps. That loose gas cap you keep meaning to replace is evaporating your fuel at a rate of about two miles per gallon.
  • Underinflated tires deflate your gas mileage by an average 3.3 percent.
  • A slipping automatic transmission can reduce our fuel economy by a mile per gallon.
  • Dirty spark plugs can cause misfires, wasting up to two miles per gallon.
  • Replacing that clogged air filter can bump up your vehicle’s fuel efficiency by as much as 10 percent.
  • If your cooling system thermostat causes your engine to run too cold, you’re losing fuel economy by two miles per gallon.
  • Worn O2 sensors cut fuel economy by three miles per gallon.
  • Running on dirty oil or going cheap for substandard oil reduces fuel economy by one mile per gallon.
  • Idling gets you zilch miles per gallon. Just turn the car off.
  • Aggressive driving gets you even less. It cuts your cat mileage by up to 33 percent on the highway and five percent in the city. And you don’t have to be a crazed speed demon. Gas mileage decreases rabidly above just 60 miles per hour.
  • Several short trips taken from a cold start can use double the fuel of a longer, multi-purpose trip covering the same distance. It’s all about a little pre-planning of your errands.
  • An extra 100 pounds of junk in your trunk drags your fuel economy down by one to two percent. Same goes for that rooftop luggage rack and other accessories. If you rarely use it, lose it. Store it in your garage until your next road trip.

All things considered, keeping up with the recommended regular maintenance can improve your vehicle’s gas mileage by an average 4.1 percent. And fixing most any serious maintenance problem, such as a faulty oxygen sensor, can boost your vehicle’s mileage by as much as 40 percent. With the way gas prices are rising seemingly every week, maintaining your car is an investment that pays off.


A close-up view of a brand-new nickel electrode spark plug for an automotive internal combustion engine.
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