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In our era of $4 a gallon gas, fuel efficiency is a major selling point for most car buyers. The EPA estimated fuel efficiency of a car is posted directly on the sticker of a new car and you can find numbers for older models by visiting this government site: Unfortunately for many buyers, the posted numbers do not seem to match up to the mpg they actually get while driving. Why doesn’t real world fuel economy match a car’s EPA estimated rating?

The main reason is that cars are tested in a laboratory under perfect conditions. There are no passengers in the car, no one is running the air conditioner, and there are no stop signs. No one leaves the car running while they run into the house for something, it never rains and head winds do not blow. Manufacturers have even been know to keep additional space between the brakes and rotors to further reduce friction and improve fuel numbers.

How To Achieve Higher Real World Numbers

While the numbers on the sticker can be achieved if you were to drive in a bubble or something, there are things that you can do to improve your real world numbers. The main factor that you can control is the speed that you drive. Not so much the top speed as running at a continuous speed. The constant acceleration and deceleration associated city driving saps fuel efficiency, that is why you see a city rating and a highway rating for every car. Cruise control can add several miles to each gallon of gas that you buy.

Other factors that are a drain on your fuel efficiency is how often you use your air conditioner, the climate you drive in, type of fuel you use, and the number of passengers that you normally carry around. Air conditioning drains fuel efficiency by increasing the load the engine is required to carry while running. Weight saps fuel efficiency in a similar way; the engine must work harder to produce the same amount of power and speed. The EPA uses 100 percent pure gasoline when testing, but the fuel available to most people is cut with 10 percent ethanol, which is less efficient. The E85 that is available is 15 percent ethanol and even less efficient.

Even though automobile manufacturers test their cars in ideal conditions that you will never drive in, the numbers can still be useful when deciding which vehicle to buy. Even though you may never see that number, you can get an idea of how two models stack up. You should also take into account the true cost of ownership of a car. When you look into that number you may not think the added cost of a more fuel efficient car is worth it. Many websites offer true cost numbers, but the most reliable may be You can find those numbers by reading a review of the vehicle you are interested in on the site.


About the author: Taylor


Taylor is the founder of He's a seasoned fiction and web writer who has been involved in the automotive industry for nearly a decade. He's currently restoring a 1985 BMW 325e. Email | Twitter | Google+


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