A World Without Gas Caps is Here

Dear Car Talk:

In a recent column, you talked about how a vehicle's emissions system monitors itself for leaks. And that if a gas cap is loose and lets vapors escape, that will turn on the check engine light.

Well, neither my 2019 GMC Terrain nor my wife's 2021 Honda Accord even have a gas cap. And I'm pretty sure they were not stolen! How is that possible? There is no way for the tank to be pressurized without a cap. And gas fumes can certainly evaporate and escape through the filler spout.

What's going on, Ray? -- Scott

Oh no. GMC and Honda forgot to order gas caps!

Actually, I think Ford was the first manufacturer to go "capless." It's not really capless. The cap is just on the inside now. It's a spring-loaded flap located just inside the filler opening. When you insert the fuel nozzle, it pushes the cap out of the way and allows you to add fuel. When you remove the nozzle, the internal cap springs back into place. It has a rubber O-ring around it to seal the filler opening and keep both gasoline and vapors from escaping. So it works exactly like a gas cap does, except you never have to remove it, replace it, tighten it or go back to the gas station because you accidentally left it on top of the pump and drove away. A week ago.

These capless filler necks have been around for years now, and they seem to work great. The only downside is that if you need to add emergency fuel -- from a can with a flexible hose, for instance -- you can damage the cap mechanism. So, several companies, like Ford and Honda, include a little plastic spout to use just for that purpose. You can check your owner's manual to see if your car has one, and where it's stored.

Think of the world without gas caps like wireless internet, Scott. The lack of a wire doesn't mean you can't check your email. It just means you no longer have a wire to trip over.

Todays Car-o-Scope

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