Keep your tires inflated to the proper levels. Under-inflated tires make it harder for your car to move down the road, which means your engine uses more fuel to maintain speed. In fact, a single tire, under inflated by two pounds per-square-inch (PSI), increases fuel consumption by one percent. Check your owner’s manual or the decal in your car’s doorjamb for correct inflation levels. To illustrate the point, deflate your tires by five PSI and try to push the car. It’s not easy. Now inflate those tires and see how pushing the car is much easier.