Dear Tom and Ray:
I have a 2003 Honda Accord coupe. Like most cars, it has three cruise-control buttons: the main on-off cruise button, the Set button and the Resume button. I use the cruise control a lot, so I just leave the main switch on all the time. My husband thinks that this is bad for the cruise control, and that it could be dangerous if I were to accidentally press the Resume button when not meaning to. To me, this does not make sense, because when the engine shuts off, it does not retain the Resume memory, and it seems unlikely that anyone would accidentally press the Resume button anyway. Can you settle this dispute for us? Is there any reason why someone would not want to leave the main cruise on all the time? — Lana
Tom: Lana, you're right that leaving the main cruise control switch in the "on" position will not harm the cruise-control system in any way.
Ray: But your husband's right that the main on/off switch is there for your safety. It's actually pretty easy to hit the Set and Resume buttons by accident, because those controls are deliberately placed within very easy reach of your fingers — like on the steering wheel or the stalk.
Tom: And if you're making a turn, or trying to switch on your wipers or blinkers, or who knows what, it's not very hard to hit one of the cruise-control buttons inadvertently. How do we know? We've done it!
Ray: Is it a disaster if you hit the Resume button by mistake? Not necessarily. Like you say, there may be no speed stored in the cruise control's memory. Or, if there is, you may quickly realize what has happened and tap your brakes to disable the cruise control.
Tom: But there are situations in which it can be a disaster. If you've been on the highway doing 70, and then hit some heavier traffic and slow down to 50, you could hit the Resume button and suddenly make the car accelerate 20 mph while in that heavy traffic.
Ray: And if you're startled and don't realize why it's suddenly accelerating, you may panic and not have the presence of mind to tap the brakes before you plow into the car in front of you.
Tom: We know that lots of people just leave the main cruise switch on all the time. It's understandable. But our recommendation (and the recommendation of our lawyers, who are standing here glaring, with their arms crossed, as we speak) is to turn off the cruise-control system when you're not actively using it. That's the safest thing to do, and it's why the switch exists.
(Car Talk is a nationally syndicated column by automotive experts (and brothers) Tom and Ray Magliozzi. Write to them at the Car Talk website.)