I read in HJs Telegraph answers column that using Cruise control in wet weather can cause the driven wheels to spin. The electronics would sense the car slowing and apply more power possibly causing a loss of control.
I thought the car sensed speed from the gearbox and if the revs increased it would sense an increase in speed and reduce power.
Or have I got it wrong?
Last edited by: Old Navy on Sat 26 Jan 13 at 20:42
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It depends.
Some cars take their speed signal from an ABS sensor.
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Would that not also indicate an increase in wheel speed causing the CC to reduce power?
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>> Would that not also indicate an increase in wheel speed causing the CC to reduce
>> power?
>>
Only if the ABS sensor used to determine the vehicle's speed happened to be the same driven wheel that was spinning up.
There are so many variables between different implementations - how cleverly the cruise control uses the information available on the car. In this respect, anyone claiming to give a definitive answer applicable to all cars is kidding themselves.
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I dont think its a good idea to use cruise control in the wet, its not as quick or sensitive as your bum, ears, brain and right foot, but certainly the last Cruise I had (a VW one) kicked itself off if revs/speed got too far out of kilter.
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Another of his little foibles. Never had any problem. Hit some standing water in the 3 series a few weeks ago - the CC came off.
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>> Another of his little foibles. Never had any problem. Hit some standing water in the
>> 3 series a few weeks ago - the CC came off.
If the wheels don't agree on speed it turns off.
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>>Or have I got it wrong?
No, he has.
HJ is a car dealer, quite a good one, but nonetheless less a dealer.
He knows no more or less about the technology than anyone else. And in my experience usually less.
He just knows the value of everything and can do a deal.
Left foot braking anybody?
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I think it depends on the vehicle application.
The Hilux auto had CC, immediately you started climbing a motorway hill being very high geared it would immediately down shift, from the engine tone it had obviously applied full throttle to maintain speed.
I experimented quite a bit and i could easily control the throttle to maintain speed without the vehicle changing down the gear in most cases.
No doubt that was an unsophisticated basic CC, but i'm wary of any system that allows the vehicle to take over throttle or brake operation (excluding standard ABS), they are not for me.
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I wouldn't worry about it.
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>> immediately you started climbing a motorway hill being very high geared it would immediately down shift
>>I experimented quite a bit and i could easily control the throttle to maintain speed without the vehicle changing down the gear in most cases.
I recently hired a Vauxhall with CC and was impressed with its economy with CC on. I couldn't match it by driving manually. I put it down to it knowing its mapping characteristics better than I could guess and it applied the appropriate throttle for the conditions.
Perhaps your Hilux knew better than you what it wanted to do, or maybe it was selecting the most fuel efficient option?
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Or perhaps it was just a crude simple truck.....
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>> Perhaps your Hilux knew better than you what it wanted to do, or maybe it
>> was selecting the most fuel efficient option?
Possibly Tom, but a paragon of fuel efficiency it certainly wasn't..;)
It was in practice a remarkably competent high speed cruiser tiddling along at 80 @ around 2k rpm IIRC, given just a gentle increase on the throttle it would maintain that speed easily without dropping a gear up all but the steepest hills.
Lovely motor to drive mind, we both miss it.
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I would think that modern integrated CC systems have inputs from many sources, ABS, Traction control, engine and transmission ECUs, ect. and as number cruncher says there is no easy or single answer.
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I think this was more dangerous for older CC, but newer ones, even in the last 10 years seem a lot more sensible, for example, they can take account of steering angle, gradient, wiper fuction, and on some expensive ones in the last 8 years and now new general ones, even GPS location to prevent shifting or accelerating on bends and of course the distance to the car in front and behind on some advanced cars.
I don't think HJ was wrong when he said it, and it is good advice for the general reader of the paper.
Last edited by: sooty tailpipes on Sun 27 Jan 13 at 10:21
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I think it's good advice anyway - he may be wrong, given the variation in implementations, but that's not the same as saying he's never right - quite the opposite.
Anyway, who doesn't want manual feel in bad conditions? And for that matter, when the system has picked up the mismatch in wheel speeds traction has already been broken.
I don't use CC in bad conditions, even though I use it all the time otherwise - just like a hand throttle in fact. I'm quite happy to trust the car to react sensibly if I hit an unexpected slippy patch, but why push your luck when you would otherwise be using very gentle, controlled inputs?
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>> I don't use CC in bad conditions, even though I use it all the time
>> otherwise - just like a hand throttle in fact.
>>
That is much like my use of CC, no one in their right mind would (should) use it if there was a remote chance of intervention from ABS, Anti skid, or Traction control systems. In fact I have never unintentionally provoked any of them into action.
Last edited by: Old Navy on Sun 27 Jan 13 at 13:22
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>> >> I don't use CC in bad conditions, even though I use it all the
>> time
>> >> otherwise - just like a hand throttle in fact.
>> >>
>>
>> That is much like my use of CC, no one in their right mind would
>> (should) use it if there was a remote chance of intervention from ABS, Anti skid,
>> or Traction control systems. In fact I have never unintentionally provoked any of them into
>> action.
>>
I'd take the opposite view, these systems are all interlinked and knowing how bad press can kill a company I'd say these systems will talk to each other and make adjustments quicker than sphincter, brain, right foot and two hands.
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>> I'd take the opposite view, these systems are all interlinked and knowing how bad press
>> can kill a company I'd say these systems will talk to each other and make
>> adjustments quicker than sphincter, brain, right foot and two hands.
Up to a point you're right - once traction is lost. But the car can't know and judge what to do to avoid that situation.
Unlike ON I often provoke the ESP/TC and ABS in the wet both for the amusement value and to know just what the innate capability of the car is. It makes it much easier to stay the right side of the line when I need to.
Last edited by: VxFan on Mon 28 Jan 13 at 10:18
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>> Unlike ON I often provoke the ESP/TC and ABS in the wet >>
I assume you saw the word "unintentionally" in my post. :-)
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>> I'd take the opposite view, these systems are all interlinked and knowing how bad press
>> can kill a company I'd say these systems will talk to each other and make
>> adjustments quicker than sphincter, brain, right foot and two hands.
Some of us don't have such control taken away from us and still know how to have fun in the slippy.
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To be fair to HJ, he was explaining the rumour which one of his readers had heard, stating this was in a "long-winded, alarmist email did the rounds a while ago". While not stating that the rumour was rubbish, saying the same could apply in icy conditions, it did not appear to me to be his viewpoint.
tinyurl.com/alb8cev
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What could this be about? One wouldn't use cruise in icy conditions anyway of course, but in ordinary wet highway conditions it wouldn't be a problem because very few cars will get wheelspin in top gear even in the wet. Of course some diesel/water mayonnaise could permit it.
I don't like it much anyway. I drive better than it does if there are any inclines. It only works well on flat roads or if you are wimpish about speed limits.
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Didn't this originate in the USA, where many people drive those traditional RWD solid axle pickups with 90:10 weight distribution?
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>> The Hilux auto had CC, immediately you started climbing a motorway hill being very high geared
>> it would immediately down shift
Work's 61-plate Hilux Invincible would downshift twice when towing uphill - the 'changes were a bit ponderous and it lost enough momentum changing from 5th to 4th to convince the CC that 3rd was immediately needed. Once in 3rd it accelerated like hell back up to the original speed, most annoying when elephant racing on the M1 at 55mph.
My Mazda6 has very similar gearbox programming and will kickdown to 4th at the first sign of a hill at 70mph. Damn thing has almost no torque either so it doesn't make a lot of difference, only a lot of noise. Whoever thought a peaky 16v VVT engine would go well with an autobox wants slapping. Back on topic, I haven't been using the Mazda's CC in the recent below-zero weather - it likes to drop a gear and give it 4500rpm with no warning, not what you want on a wet, slimy motorway curve.
Last edited by: Dave_TDCi on Mon 28 Jan 13 at 22:18
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If you believed everything HJ says in his column then you would never drive he contradicts himself what is good one week with a certain car is bad the following week.
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I treat motoring journalist and pundits with the contempt they deserve. I have never paid attention or used their advice in any car purchase I have ever made since passing my test in 1956.
Even magazines such as Whatcar, just to name one, are OK to peruse very very occasionally but there again there are many contradiction and errors in their New Car data at the back and what annoys me most is the inability to remain consistent and accurate when stating a car's width - sometimes including mirrors and sometimes not.
Sometimes the best sort of information can be found in Wikipedia!
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+1
IIRC a road test of some BMW by Autocar ?which stated how wonderful it was, best car they had ever driven etc etc.
Then as a throw away line, something about hard suspension makes it very uncomfortable on rough roads and speed humps are something you may wish to avoid to save your back.
Written in my view by pre pubescent schoolboys.
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Car salesmen and journalists must be from the same mould. :-)
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>>I treat motoring journalist and pundits with the contempt they deserve
I wish you had said "typical car reviews" rather than tarring motoring writers with one brush. Perhaps you didn't mean it that way. I know and have met some excellent motoring writers.
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HJ wrong? - Number_Cruncher
