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5 Mechanical Problems that Decrease your car’s Fuel Economy

Fuel Economy

Nobody wants to spend money to fix a car that’s not broken, but nobody wants to spend more than they have to at the gas pump either.  We all know there is that direct link between the fuel economy our car gets and its mechanical condition.  Here’s a few things you might not realize can affect fuel economy.

  1. Misalignment of tires.  One of the highest fuel consumption threats your vehicle can have relates to the alignment of the front tires.  Improper alignment decreases fuel economy by increasing the rolling resistance of your vehicle.  Picture walking with your feet pointed out, like a duck, at a 15 degree angle.  Then, rather than picking them up as you walk, just drag them along the ground.  How efficient would that be?  This can cost you a mile or two per gallon.  On a car that gets 20 miles per gallon (MPG) that is a 5 to 10 percent reduction in fuel economy.
  2. Driving with the park brake partially on.  This OOPS can cost you a mile or two per gallon and decrease your fuel economy by 3 to 8 percent.  The expense of lost fuel, however, may be small compared to the price tag you’ll see for damage done to your brake pads, shoes, drums or rotors.  Failing to notice your park brake is on when the car is in motion can wear out your brake linings incredibly fast, which results in a metal to metal friction that can destroy expensive brake drums and rotors.
  3. Transmission or clutch that slips.  Fuel economy is reduced by 5 to 10 percent when slippage reduces the normal amount of power going directly to the tires as they move the car forward and the driver has to push the accelerator down farther to get to the desired speed.  What can cause an automatic transmission to slip?  Too many things than could be covered in this article, but one easy prevention measure is to be sure the automatic transmission fluid is neither dirty nor at too low a level.
  4. A thermostat that has failed.  Engines are designed to run most efficiently at a specific temperature.  A cold engine needs more fuel than a warm engine.  It is the engine thermostat that gets the engine to the correct temperature as quickly as possible so it will require less fuel.  Because almost all cars and trucks today have a computer that controls the fuel system, any mechanical problem with the thermostat that causes the engine to run colder than it should may cause the computer to adjust and send more fuel than is required.  The additional fuel could reduce your fuel economy by 2 miles per gallon or more.
  5. A bad battery.  Bet that’s one you may not have thought of as a cause for poor fuel economy!  Remember, what charges the battery is the alternator, and what turns the alternator is a drive belt powered by the engine.  This means the alternator consumes energy from the engine, and if it has to work harder to try to keep a bad battery charged, then it stands to reason more energy will be consumed as it is forced to work more.  The result is reduced fuel economy.

Who likes to spend money on their car?  Nobody I know, but when spending money can end up saving you money its helpful to know how to spend wisely.  Hopefully you’ll find these tips helpful as you try to make better decisions about how to spend your car repair dollars.

Copyright 2009 Dave Eastman, ADSi.  All rights reserved.   This post subject to Dale’s Auto Care website copyright as approved by Dave Eastman. (for verification email dave at daveeastman.com)

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