Tom and Ray retract: some cruise control systems DO have the ability to slow a car going down hills.

Dear Car Talk

Dear Car Talk | Apr 01, 2002

Dear Tom and Ray:

Usually your advice and comments are not only scintillating, but also accurate. Alas, I am forced to come to the defense of the poor father-in-law you wrote about a few weeks ago. He wanted to know if his cruise control could slow his car down. Being of the age when I could soon become a father-in-law, I realize that we have to stick together. You told him that his cruise control operated the throttle only (that might be true for his Taurus). But my car's cruise control does reduce speed on a long grade. Recently, we were driving our '98 Dodge Caravan through the Pennsylvania mountains. At least three times, running down a long hill, when the car started to outrun the cruise-control settings by more than about 5 mph, it would shift into a lower gear. I could see the tachometer jump when it downshifted. So, while I hesitate to call into doubt advice from the Western World's foremost authorities on all things automotive, I have to do so in this case. -- Ed

TOM: Look, Ed. If you want to call our advice into question, you'll have to get in line -- and the line currently stretches to somewhere in the Pennsylvania mountains.

RAY: I have to give credit to my brother. He told me that he thought "some car" he had driven had downshifted under cruise control to slow the car. I told him he had his headlight in his taillight socket (which is usually a good bet). But it turns out he was right.

TOM: We got letters from hundreds of Chrysler minivan owners who told us the same story you did, Ed. So we called Chrysler, and you're absolutely right. They have a system that can downshift to slow a car.

RAY: Most cruise-control systems (let me save a little face here) do operate only the throttle. But this one -- and there might be others out there by now -- can also operate the car's electronically controlled transmission (automatic only, of course). So if you exceed the cruise-control setting by a lot, it can shift the transmission into a lower gear and use the engine's natural braking power to slow you down.

TOM: So we'd like to apologize to fathers-in-law everywhere and give a belated dope slap to the son-in-law from the original letter who doubted the old man. And one for my brother for doubting me, too.

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