Gas tank caps: They play an important part in your car's fuel system, even setting off a check engine light on the dashboard if they go missing or aren't screwed on correctly after refueling.

Refueling cars is a standard procedure, but not every car has its gas cap on the same side, with some on the left, some on the right. There's a good reason why.

At the gas station, pump handles come in three colors: yellow, black and green. Be careful -- making the wrong choice can harm both your mileage and your car.