Maintaining your car's tires is one of the easiest ways to save on money at the gas pump. Your car's manufacturer provides the recommended air pressure for the tires both in the owner's manual and on a sticker in the driver's doorjamb. According to the United States Department of Energy, an average car's gas mileage decreases by .3 percent for every 1 psi of tire pressure lost in all four of a car's tires. Also, if your car's tires are worn out, they will slip on the road instead of gripping the surface, causing your car to use even more gas.
Remove roof racks, roof pods and luggage carriers if you are not going to be using them in the immediate future. Anything that mounts to the outside of your car negatively impacts its aerodynamics. This means your car's engine has to work harder to maintain the same speed on the road, increasing how much gas it consumes.
Check the air filter regularly. Most air filters are located in the engine compartment, inside a black plastic box that is secured with metal clips. The air filter literally filters particles out of the air, such as dust or pollen, before they enter the engine and cause problems with its operation. If the air filter accumulates too much debris, it begins starving the engine for oxygen, causing it to burn more fuel. Replacing the air filter regularly lowers your car's gas consumption.
Combine trips whenever possible. This takes conscious thought and planning, instead of you just hopping in your car and running errands on a whim. If you want to go out to eat, but you also need to swing by the dry cleaners or run other errands, try to do them all at the same time, especially if they are in the same general area of the city.
Avoid idling your car's engine whenever possible. Some hybrid vehicles actually shut off the engine when the car is stopped, turning the engine back on when the driver takes his foot off the brake pedal. Idling produces unnecessary pollution and burns gas when you are going nowhere. The next time you are waiting for your food at the drive through or are waiting in line outside the bank, turn off your car's engine unless you are moving forward.
Use air conditioning instead of rolling down your windows. In most modern cars, the air conditioner's compressor places little load on the engine, affecting the car's gas mileage only slightly. Rolling down the car's windows affects the car's aerodynamics, meaning the engine uses more gas. Remember that using the air conditioning not only feels better, but it also saves gas.
Follow your manufacturer's recommendation for engine oil. Using the wrong type of engine oil decreases the engine's efficiency, lowering its gas mileage. Most cars have the recommended oil printed on the engine's oil cap. If you don't find the recommended oil on the cap, check the owner's manual.