A broken or missing gas cap can reduce your fuel efficiency by 2%.

Your Broken or Missing Gas Cap May Be Costing You Money
A broken or missing gas cap can reduce your fuel efficiency by 2%.
By Josh Peterson
Los Angeles, CA, USA | Tue Jun 16 14:30:00 EDT 2009

There are a lot of lids in this fast-paced, modern world. There are lids for ketchup bottles. There are lids on Tupperware and lids on manholes. This one guy that I know has a big container with nothing but lids inside and the lid-filled container has its own lid. There is even a store at the mall called Lids that sells hats, but I don't go there. I'm not a hat person. I'm a lid person.

Today, I want to talk about a very special lid, a lid that we hate to see but know all too well. That lid is the gas cap. It is like a little, round doorway for petrol on the side of our car.

The gas cap is one of the few pieces of the car that can be completely removed and left behind without being immediately noticed. If you left the passenger door or the rear axle on the roof of the car, you would probably notice almost immediately.

Gas caps become orphans every day. There are some who believe that lidlessness is no big deal. But those some are wrong. A broken or missing gas cap can reduce your fuel efficiency by 1% to 2%. You see, the gas cap keeps evaporates and --believe it or not--gas in its proper place. Those evaporates will get used by your car, but if there is no cap, the evaporates will pollute the air with no benefit to you or anyone really.

Listen for the Hiss

A missing gas cap is an easy mystery to solve, but trying to figure out if you have a loose or poorly fitting cap can be a tad more difficult. Car Junky suggests a simple listening test. While unscrewing the cap, listen for a hiss. The hiss means that your gas cap fits well.

What is a Gas Cap good For?

The gas cap also keeps dirt and other contaminates out of your gasoline. Gunk in your gas can reduce fuel efficiency and hurt your car.