Loose gas caps, underinflated tires, faulty thermostats,
worn spark plugs, malfunctioning engine controls, poor
wheel alignment and the list goes on. These are among
the conditions that daily cost consumers millions of
dollars in wasted fuel.
“Something as innocuous as an improperly tightened
gas cap, for example, or one that’s missing or defective, might seem a minor factor,” said Rich White of the Car Care Council. “But consider that 17 percent of the vehicles on U.S. highways have either misused or missing gas caps, causing 147,000,000 gallons of gas per year to vaporize into the atmosphere (source: Service Tech Magazine, 
September 2000).
“To the maxim ‘waste not, want not,’ we need to add ‘be car care aware,’ because most drivers are unaware of the economic consequences of neglected maintenance.”
White said the nearly 150 million gallons of gas out of
the filler cap are literally a drop in the bucket of waste.
“Among the six worst offenders are underinflated tires and incorrect wheel alignment, conditions which increase rolling resistance. Like driving with the parking brake not fully released, it can cost a mile or two per gallon on a car that normally delivers 20 miles per gallon. “Among other gas
guzzlers,” said White, “are dirty oil, a mile per gallon; a slipping automatic transmission, another mile per gallon
and as much as two mpg for a cooling system thermostat that causes the engine to run too cold.
Some of the above statistics were gathered from a U.S. Department of
Energy Web site, www.fueleconomy.gov
You can improve your gas mileage by 1-2 percent by using the manufacturer’s recommended grade of motor oil. For example, using 10W-30 motor oil in an engine designed to use 5W-30 can lower your gas mileage by 1-2 percent. Using 5W-30 in an engine designed for 5W-20 can lower your gas mileage by 1-1.5 percent. Also, look for motor oil that says “Energy Conserving” on the API performance symbol to be sure it contains friction-reducing additives.
3.3 percent by keeping your tires inflated to the proper pressure. Under-inflated tires can lower gas mileage by 0.4 percent for every one psi drop in pressure of all four tires. In addition, properly inflated tires are safer and last longer.
