Even if you can't afford a hybrid car, you can keep track of your tire pressure to increase fuel efficiency. Find out from your car's manual what the maximum pressure is for your tires -- it's usually around 35 pounds per square inch (PSI) for most. Then invest in a tire pressure gauge to make sure each tire has the correct PSI. If any is low, you're decreasing your fuel efficiency. If that's the case, pop some quarters into the air machine at the gas station and fill them up until they reach their maximum PSI.