The National Automobile Dealers Association (NADA) has launched a Green Checkup campaign, empowering local dealers to help customers save gas, reduce emissions, and improve fuel economy through vehicle maintenance. NADA's 10-Point Green CheckupMotor oil. Top off and change oil as necessary with manufacturer-recommended grade, "energy conserving" motor oils. Doing so can improve fuel economy by up to 2 percent, according to the U.S. Environmental Protection Agency (EPA). Replacing conventional oils with synthetics may offer even greater fuel economy benefits.Air filters. Make sure you change your air filter at the end of its recommended lifespan. Replacing a clogged air filter can improve a vehicle's gas mileage by up to 10 percent, according to the U.S. Department of Energy.Engine performance. Enhance fuel economy performance by having engines tuned and spark plugs replaced according to the manufacturer's recommended schedule. A single misfiring spark plug can cut fuel economy by up to 4 percent, according to the EPA.Brakes. Improperly maintained brakes can result in unwanted drag. This unnecessary resistance can have the same effect as driving with a foot on the brake pedal: a dramatic drop in fuel economy.Warning lights for "Service Engine Soon" or "Check Engine." Ignoring these indicators may result in poor fuel economy performance and require expensive repairs. For example, a warning light may indicate a faulty oxygen sensor is sending more fuel to the engine than necessary, which can result in a 40 percent fuel economy decline. A warning light could also indicate a faulty thermostat, which can prevent a cold engine from reaching its normal operating temperature resulting in the unnecessary injection of fuel.Tire wear. Replacing worn tires with a manufacturer-recommended size and style can save hundreds of dollars a year. To improve fuel economy performance, consider low rolling-resistance replacement tires.Tire inflation pressure. Keeping tires inflated to at least the manufacturer-recommended pressure can improve fuel economy by up to 3 percent, according to the EPA. Under-inflated tires require more energy to roll, meaning more fill-ups.Unnecessary items that add weight to the vehicle. Unnecessary weight lowers fuel economy; remove heavy items from your trunk and back seat.Evaporative emission controls. Poorly operating evaporative emission controls can fail to capture gasoline vapors and recycle them to the fuel tank. Faulty controls waste gas and degrade air quality.Transmission. Properly operating modern transmissions and drive components are critical to vehicle fuel economy performance. Routinely check proper fluid levels and system operation.The publicized goals are admirable, but do filter your local dealers’ recommendations through an understanding that dealer profits are down and the service center can drive their revenue. More tips and advice are presented on the EcoDriving Web site, cleverly hosted by Governator Schwarzenegger.For more car maintenance advice, browse our Car Care archives.