Condition

Under inflated tires

Dirty air filter

Worn spark plugs

Worn O2 sensor

Dirty or substandard engine oil

Loose gas cap

Potential loss in fuel economy if all of the above were neglected 

Effect

 Increase rolling resistance

 Causes excessively rich fuel/air mixture

Cause inefficient combustion, wasted fuel

Unable to detect and adjust air/fuel mixture 

Increases internal engine friction

Allows fuel to evaporate

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MPG Penalty up to

 1-2 mpg

 2.0 mpg

2.0 mpg

3 mpg

0.4 mpg

2.0 mpg

11.4 mpg

The Car Care Council offers these fuel-saving tips:

• Vehicle gas caps -- About 17 percent of the vehicles on the roads have gas caps that are either damaged, loose or are missing altogether, causing 147 million gallons of gas to vaporize every year.
  
• Under inflated tires -- When tires aren't inflated properly it's like driving with the parking brake on and can cost a mile or two per gallon.
  
• Worn spark plugs -- A vehicle can have either four, six or eight spark plugs, which fire as many as 3 million times every 1,000 miles, resulting in a lot of heat and electrical and chemical erosion. A dirty spark plug causes misfiring, which wastes fuel. Spark plugs need to be replaced as recommended by the manufacturer.
  
• Dirty air filters -- An air filter that is clogged with dirt, dust and bugs chokes off the air and creates a "rich" mixture -- too much gas being burned for the amount of air, which wastes gas and causes the engine to lose power. Replacing a clogged air filter can improve gas mileage by as much as 10 percent, saving about 20 cents a gallon.
  

Fuel-saving driving tips include:

• Don't be an aggressive driver -- Aggressive driving can lower gas mileage by as much as 33 percent on the highway and 5 percent on city streets, which results in 10 to 66 cents per gallon.
  
• Avoid excessive idling -- Sitting idle gets zero miles per gallon. Letting the vehicle warm up for one to two minutes is sufficient.
  
• Observe the speed limit -- Gas mileage decreases rapidly at speeds above 60 mph. Each mpg driven over 60 will result in an additional 10 cents per gallon. To maintain a constant speed on the highway, cruise control is recommended.
  

WIPERS - In the 2001National Car Care Month vehicle check lanes, 21percent of participants had wipers that smeared, streaked or chattered across their windshields. Although climates vary, wipers generally need replacing every six months. An easy reminder is to change wiper blades in the spring and fall when you change your clock. Be sure the windshield washers are working properly, too, and keep the reservoir filled with solvent.

LIGHTING - Another important pre-trip check should be exterior and interior lighting. Vehicle check lanes revealed an overall failure rate of over 25 percent in the lighting category. The Car Care Council reminds motorists to check their lights monthly. Other suggestions from the Council include turning on headlights both day and night. This helps define your car's position on the road, and its distance from other drivers. When your vehicle's lighting is defective, other motorists may not get the message that you intend to stop or turn. The end result could be disastrous.

10 Minute Pre-Trip Checkup Can Pay Off

Car Care Council offers three suggestions for a traveler's 10-minute pre-trip checklist:

• Check all fluids. There are several fluids, in addition to antifreeze, that require attention, including engine oil, power steering, brake and transmission fluids and windshield washer solvent and antifreeze/coolant.
  
• Check hoses and belts. A belt that fails can affect the electrical system, air conditioning and power steering, as well as the cooling system. Cooling system hoses may be deteriorating from within, so old hoses and clamps in marginal condition might need to be replaced.
  
• Check the tires. Check tire inflation and inspect the tread for uneven wear, indicating the need for wheel alignment. Also look for bulges and bald spots.
  

"While a last minute checkup is better than no checkup, motorists should plan ahead to allow time to perform necessary maintenance themselves or at the local service facility. A properly maintained vehicle is safer and more dependable and will even save a few dollars at the gas pumps," said the Car Care Council's Executive Director, Rich White.

Not only can a pre-trip inspection help reduce chances of costly and possibly dangerous road trouble, it also provides an opportunity to have repairs made at home, with one's own technician who knows the vehicle. Especially important, it provides peace of mind. While no inspection can guarantee a car's performance, it's comforting to know proper precautions were taken.