Every car with cruise control that I’ve driven has an on/off switch that is independent of setting the speed you want to go. I.e. you can’t set a speed until you turn it on first, but there’s no noticeable difference between driving with the cruise control on and no speed set, and driving with the cruise control off.
Why is that? What is the cruise control doing when it is on but no speed is set that it couldn’t either just be doing all the time, or do immediately when you set a speed? Why do we need a separate button to push?
One thing that you can do is, after turning it on, getting up to speed and setting cruise, if you then use your brake pedal or hit cancel to turn it off, you can hit resume to get the car back to the previous speed. That also means you can, from a stop, bring the car back above the minimum speed, hit resume, at the car will accelerate (albeit slowly) to the previously set speed.
I suppose turning it off makes sure that if you bump the ‘resume’ button by accident, nothing happens.
It’s automaker dependent, and which way they go is just “the done thing.” There is one difference in functionality, though; in most systems (at least the ones I’ve encountered) if you cancel the cruise setting by a different action (pressing the brake or clutch) then the “resume” button will implement the previously set speed. If, however, you cancel the cruise setting by pressing the “off” button, then the “resume” button does nothing.
You will occasionally find a dealer telling you that leaving it on all the time will wear it out. I suspect that’s BS. Still, I heard this line for the first car I ever had with cruise control, on which the cruise control eventually DID stop working. I DID tend to forget to shut the thing off.
On my current car, when the cruise control is on, it displays the setting in the area where the odometer mileage is normally displayed. That provides an irritant which makes me shut it off when I’m done with it.
ETA: Sorry, what I mean is that you have to do something twice to initiate it, and an inadvertent push won’t send you unavoidably hurdling through an intersection.
Really? I’ve never driven one that didn’t have a separate on/off switch.
True that in a hypothetical (or real) CC system without an OFF state, you never lose your set speed even if it’s no longer releavant, but there’s never any problem modifying your set speed either, so the difference in functionality is between “button does something you don’t want it to do” and “button does nothing”.
The only thing I can see is Joey P’s mention of safety if you accidentally hit the wrong button, but it seems like unless hitting the resume button slams on the accelerator to get to the set speed, that’s a fairly minor issue.
My mom believed that (but she also believed a whole bunch of not-true things). That’s why I wonder if there is some kind of mechanical articulation engaged in the “on but not tracking” state.
But even if there is, why can’t it stay un-engaged until I tell it to hold a speed.
With modern display technology, I’d think it would be easy to make an unobtrusive little pointer appear with the CC set speed around the edge of the speedometer.
On some cars, the on/off setting is temporary, and will revert to “off” when the ignition is shut off.
On others, Audis and Volkswagens at least, the on/off switch for cruise control is persistent. It’s generally a positional switch (not a toggle button) that stays where you put it. On these cars, while you still have to turn cruise control on to use it, you don’t have do that every time you drive the car. On my car, I don’t think I’ve pushed the stalk to the “off” position since the day I bought the car.
Another reason for them is that back in the days of finicky electro-mechanical cruise control systems, you needed to be able to physically cut power to the CC unit in case the thing went nuts and started accelerating on its own, which was not unheard of.
A lot of the early cars with cruise control actually had a dial that moved a little needle on the speedometer face, which is how you set what speed you wanted to hold. On some cars, if you didn’t get the cruise control option, the dial-and-needle interface was still there but just served as a “speed alerter” which squawked at you if you drove over a set speed. I remember in my younger days being annoyed at such a car that wouldn’t let you set the speed alerter over 90, even though the speedo went to 120.
I could see a situation where you used it on the freeway at 55, hit cancel (or used the brake) when you exited the freeway. Now, while on a surface road traveling at 40ish and bumping resume by accident not realizing that you’re creeping back up to 55. It’s somewhat subtle, especially if there aren’t many other cars on the road to make you aware of how fast your traveling.
Interesting. I asked the same question 6 years ago. Didn’t get a satisfactory then.
I suspect that GreasyJack’s answer is the main one and the on-off switch has mainly been kept from inertia (“we’ve always had an on-off switch on the cruise control”).
We have a Jaguar XF that has no separate ‘on’ switch, and my last car, a Ford Mondeo, didn’t have one either. I agree that it’s just a matter of convention.
My Honda has not one but two buttons that will cancel or shut off cruise control (as well as the brake). Once in a while I accidentally bump one of the buttons and don’t discover it until I set the speed and then notice my speed is dropping below the speed limit, to the consternation of those behind me. Kind of annoying, and a probably small potential for hazard from unexpected deceleration, but of course not as big a hazard as unexpected acceleration.
I guess I’m not understanding this. My car (a Toyota Camry) has an on-off cruise control. When I’m driving at a speed I want to maintain, I turn the cruise control on. Then I can take my foot off the gas and the car will hold that speed.
How would it work having a cruise control that was always on? If I was driving along at sixty mph and took my foot off the gas, would the cruise control hold that sixty mph speed? What if I had taken my foot off the gas in order to slow down?
That’s the way all mine have worked. There is no such thing as on without a speed having been set. What would be the point?
My favorite story about the perils of cruise control is the guy on the deadly Hume, heading from Melbourne to Sydney. On the old road you hit Wodonga and took a left to head off through Albury. However, if you have the cruise control set on 120 kph and fall asleep at the wheel, you don’t even brake as you shoot through the intersection and into the trees.
Note the “on” / “off” button on the end of the “resume” / “set” stalk. That would appear to be a control similar to what the OP is talking about. I presume you can turn the CC on and off with the button, and when it’s on, push the stalk down to set the speed or up to resume. What happens if you turn the thing on and never turn it off after you brake, simply setting the speed again whenever you wish to have the cruise control?
Like the OP says, most cruise controls I currently see on cars seem to have some variant of this, either with a dedicated stalk, buttons on the steering wheel, or lots of controls integrated into the turn signal stalk, with a bit you twist or push for the CC. On my VW, it’s done the latter way, with lots of ways you can flip, waggle or push stuff on the turn signal stalk:
Again, I could presumably set the switch on the top of the stalk “on”, leave it, and press “set” whenever I felt like having cruise control. As I noted above, setting it “on” replaces the odometer portion of the display (the cumulative reading, not the trip odometer), which always reminds me to turn the thing off.
Yeah, decades ago I remember a great uncle who had a big old “land yacht” car of some sort with that “squawker” arrangement. When somebody suggested an indicator on the speedometer, I remembered it, too.
Mine is always in the on position, for whatever reason I just never turn it off. If you get in my car, get it above the minimum speed and hit the resume button, nothing at all will happen because no speed is set. After turning cruise on (in my case, it’s already on), I have to set (or re-set since it’s been cleared out since the car has been turned off since the last time it was set) the speed before I can take my foot off the gas.
I’m not sure if that’s what you meant though.