Should I lock the doors while I'm driving?

Dear Car Talk

Dear Car Talk | Nov 01, 2000

Dear Tom and Ray:

Perhaps you two can settle an argument I've been having with my mother for years. Is it absolutely necessary to lock my car doors while I'm driving? She grew up in the 1940s and '50s, and she says that a door could go flying open as you are zooming down the highway. I say they must have fixed that problem long ago. Your thoughts? -- Quentin

RAY: Yeah, I think they solved the "doors-spontaneously-flying-open" problem some time ago. It happened to my brother a few times in the '50s, which partially explains his mental state today. Not to mention the shape of his head.

TOM: But the bigger concern about doors is that they stay closed in the event of an accident. There are a couple of OBVIOUS reasons for having the doors stay closed in a crash: 1. It's harder to fly out of the car if the door is closed. 2. If you get banged around sideways into another car or a telephone pole during an accident, it's good to have a steel door between you and it.

RAY: But perhaps most importantly, the doors play a crucial role in the structural integrity of the car DURING an accident. The body of the car is designed to absorb the impact of a collision so YOUR body doesn't. And the doors are key structural parts of the car's body.

TOM: So if the doors fly open, the car is more likely to be crushed -- along with you inside it.

RAY: So does locking the door increase the likelihood that it will stay closed in an accident? Maybe a little. But the federal standard for UNLOCKED door latches is pretty darned stringent. The standard assumes that people won't lock their doors, so it requires that unlocked doors be able to withstand at least 2,500 pounds of pressure without opening. And that's a lot.

TOM: Depending on the individual design, some locking mechanisms might add a few more pounds to that standard. Others might not. So it doesn't hurt to lock the doors, but it's not crucial to your ability to survive a crash.

RAY: It can, however, help thwart carjackers and overly aggressive squeegee men. So it's not a bad idea anyway.

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