My dad recently turned to me and asked me a random question: “Why does my BMW 5-Series have a gas cap?” He thinks I know a lot more than I do because I write about cars for a living. I told him, “You know what? I have no clue. Let me look into this.”
It’s a mystery to me. All of my cars are old. Two of them are from the 1990s (sorry, that’s old in car years). Mine all have caps. I thought it was normal. But apparently, many new cars don’t have fuel caps. Why is that? Let’s start there.
Here is why modern cars don’t have gas caps
When I am getting gas, unscrewing a gas cap hasn’t been on my mind. Ever. The most annoying part is the price, clearly. Some do argue, however, that it can get annoying. Maybe if you forget to put it back on and drive off. Or if it has gas making it all greasy.
So… Why did car companies get rid of gas caps? What’s the point?
These days, car companies have switched from the gas cap to a new technology that does the same thing: a spring-loaded flap that seals the filler neck shut. When you push the fuel nozzle through it, it folds back. Then it pops back into place once you remove the nozzle. It’s basically the same thing, but without having an extra piece to keep track of.
This is due to convenience, sure, but the new system also reduces emissions by releasing fewer fuel vapors. Another benefit is stopping people from stealing your fuel.
The one downfall? If you’re not fueling at a pump, you may find it difficult to fill from a can without a funnel. Even with the funnel, you can’t siphon gas from the fuel tank without help.
So now, why does BMW still use a cap? BMW claims it’s to “ensure an absolute hermetic seal.” The goal is to stop fuel vapor from escaping and pressurize the fuel systems to keep it all stable. When you drive aggressively, the cap eliminates the risk of fuel sloshing around. Guess I’m glad that my cars all have a gas cap.
