Dear Car Talk:

While driving, my husband does something that makes me crazy (I know, right?). When backing out of our driveway or a parking spot, he shifts into drive while the car is still rolling backward! Is this hurting his automatic transmission?

He recently bought a used 2012 Chevy Traverse in University-of-Wisconsin Badger red -- a dream car that he wants to keep for a very long time.

I remember being taught not to shift gears while the car was still moving in the opposite direction. I know car technologies have come a long way since I began driving 45 years ago. Is the old rule of bringing the vehicle to a full stop before shifting between reverse and drive still applicable?

I'm not trying to garner an "I told you so" advantage by writing (OK, OK, maybe I am); I'm just trying to help my husband protect his beloved Chevy Traverse. He won't listen to me, but he'll listen to you -- we both read and enjoy your column regularly. If I'm wrong, I'll shut up (at least about the shifting).

Thanks for all the great information and humor you relay in your column! -- Michele



In a perfect world, Michele, no one would shift into drive while still rolling backward. Of course, in a perfect world, no one would have to worry about making their 2012 Chevy Traverse last forever, either.

So we live in an imperfect world, Michele. And in the real world, a lot of people do what your husband does. I would say that as long as you're going less than a mile or two per hour, you're doing minimal damage to your transmission by shifting from reverse to drive.

There's a certain amount of "slop" built into automatic transmissions. The propulsion is conducted through a viscous fluid (automatic transmission fluid). So it's not as if there's a hard, mechanical connection that, from one second to the next, goes BLAM, and slams all the parts together. Fluid absorbs some of that transition.

Think about stopping at a traffic light while facing up a steep hill. When you take your foot off the brake, your car will start to roll backward a little bit before the power is transmitted through the fluid and the car begins to move forward. The same thing is happening when you shift before you're fully stopped.

Is it good for the transmission? No. But at that low of a speed it's unlikely to be doing much harm, either. If, on the other hand, your husband is backing out of the driveway at 4 or 5 mph, and, instead of the using the brakes at all, he shifts into drive to stop the car and move it forward, I think he's probably shortening the life of his automatic transmission, and you are within your rights to administer a dope slap, Michele.

And if his goal is to baby this University-of-Wisconsin-Badger-red Traverse, then I think he should make every effort to come to a full stop before shifting. Why not? It can only help. Plus, it's a two-for-one. With one simple action, he can potentially extend the life of his car, and stop ticking off his wife.