• Follow maintenance recommendations in your owner's manual. An out-of-tune engine can increase emissions and fuel consumption by as much as 15 percent. Always follow your car manufacturer's suggested tune-up schedule to ensure your vehicle is performing at its best.

• Upgrade your motor oil. Some of the newer high-performance synthetic motor oils have been proven to significantly reduce emissions.

For instance, according to independent tests, Royal Purple motor oil has been shown to reduce carbon monoxide emissions by as much as 62 percent when compared to conventional petroleum-based oils.

It also improves fuel economy by as much as 5 percent and produces notable horsepower and torque increases. So you can switch to an environmentally friendly product without giving up performance.

• Regularly replace your car's air filter. A clogged air filter can increase fuel consumption by as much as 10 percent. Air filters keep impurities from damaging the interior of the engine, so replacing dirty filters will save gas and protect your engine.

• Keep the tires of your vehicle properly inflated. The U.S. Energy Department reports that underinflated tires can increase fuel consumption by up to 6 percent.

One study estimates that 50-80 percent of the tires rolling on U.S. roads are underinflated. It's estimated that Americans could save up to 2 billion gallons of gas each year simply by properly inflating their car's tires.

• Avoid topping off your gas tank. Topping off releases gas fumes into the air and cancels the benefits of the pump's anti-pollution devices. Capping your tank once the pump automatically shuts off is safer and reduces pollution.

To learn more, visit the following Web sites: www.epa.gov, www.fueleconomy.gov, or www.royalpurple.com.

Keep the tires of your vehicle properly inflated. The U.S. Energy Department reports that under-inflated tires can increase fuel consumption by up to 6 percent.