Question — 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.
Question — We have a '95 Toyota Corolla DX with 77,000 miles on it. After driving slowly up an incline and then going onto flat ground, the engine noise changes. The noise sounds like pebbles or sand particles floating at the bottom of a vessel. This happens, for example, when I go up my driveway and then into the flat garage. I only hear this noise when the car is moving slowly. When cruising, the engine purrs smoothly. Any ideas? — Prasad
RAY: I would guess it's an exhaust system noise, Prasad. When you drive up a hill, you shift the geometry of the car's suspension.
TOM: And then when you reach flat ground, you shift it back again. My guess is that during this transition, some part of the exhaust system touches the underside of the car and vibrates a little bit.
RAY: It might be happening at higher speeds, too. But at higher speeds, all the car's other creaks and groans, plus the wind and tire noise, drown out the exhaust noise, and you don't hear it.
TOM: My guess is it's benign, Prasad. But if you want to put your mind at ease, try to duplicate the noise for your mechanic. The only hard part will be finding a mechanic whose garage is up a hill from his driveway. Good luck, Prasad.
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The Magliozzi brothers' radio show, "Car Talk," can be heard Saturdays at 10 a.m. and Sundays at noon on KUER FM 90.1, and on KCPW 88.3/105.1 FM Saturdays at 9 a.m. and Sundays at 10 a.m. If you have a question about cars, write to Click and Clack Talk Cars c/o King Features Syndicate, 235 East 45th St., New York, NY 10017. You can e-mail them by visiting their Web site at www.cartalk.com