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This went out around my company as a safety message. I myself don't use cruise control on wet roads anyway - just seems like common sense to me - but I'm not sure if this explanation seems right to me. I can't imagine wheels speeding up when they lose contact with pavement. Having less resistance on them, they might only try to maintain their speed of rotation. Is there any scientific substance to this story, and is there any accepted thinking on using cruise control on wet, rainy, or icy road surfaces? The message follows:

A 36 year old female had an accident several weeks ago and totaled her car. A resident of Kilgore, Texas, she was traveling between Gladewater & Kilgore. It was raining, though not excessive, when her car suddenly began to hydroplane and literally flew through the air. She was not seriously injured but very stunned at the sudden occurrence !

When she explained to the highway patrolman what had happened he told her something that every driver should know - NEVER DRIVE IN THE RAIN WITH YOUR CRUISE CONTROL ON. She had thought she was being cautious by setting the cruise control and maintaining a safe consistent speed in the rain.

But the highway patrolman told her that if the cruise control is on and your car begins to hydroplane - - when your tires loose contact with the pavement your car will accelerate to a higher rate of speed and you take off like an airplane. She told the patrolman that was exactly what had occurred. We all know you have little or no control over a car when it begins to hydroplane. You are at the mercy of the Good Lord. The highway patrol estimated her car was actually traveling through the air at 10 to 15 miles per hour faster than the speed set on the cruise control.

The patrolman said this warning should be listed, on the drivers seat sun-visor - NEVER USE THE CRUISE CONTROL WHEN THE PAVEMENT IS WET OR ICY, along with the airbag warning. We tell our teenagers to set the cruise control and drive a safe speed-but we don't tell them to use the cruise control only when the pavement is dry.

The only person the accident victim found, who knew this ( besides the patrolman ), was a man who had had a similar accident, totaled his car and sustained severe injuries.
 

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On older vehicles, perhaps, but our VDC would counter this, plus our cruise will not work if the windshield wipers are on.
 

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I doubt the accuracy of the story, but there is some merit in the warning. Several organizations warn against using cruise control when road conditions are slippery. If you're driving without cruise control and you hit a wet or slippery patch, good drivers will try to correct for it by easing off the gas. In general it is not a good idea to hit the brakes when this happens. The problem with cruise control is that it will continue to rev the engine to maintain whatever speed you have set, so if you go into a curve and hit a wet patch, it's harder to recover control. Some people say that they can disengage cruise control by tapping the brake, but there are two points that go against that:
1. It is not "natural" to tap the brake when your car starts to slip, so many people will not instinctively do so.
2. Even if one could tap the brake, it would probably take longer than just easing off the gas if the cruise control were not engaged.

As for whether the car actually accelerates if you're in cruise control and start to hydroplane, I think that's hogwash. If anything, when wheels lose traction they will tend to spin faster (because of lack of resistance) and the cruise control will actually reduce rpm to bring the wheels back to the speed that you had set. So when the wheels get traction again, the engine will probably accelerate to get you back to the speed that was originally set. But I don't see how the vehicle can actually travel 10 to 15 miles faster through the air than the speed that the cruise was set at.
 

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plus our cruise will not work if the windshield wipers are on.
Hmmm, is that a fact? I have to test this...
 

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MustGoFastR said:
On older vehicles, perhaps, but our VDC would counter this, plus our cruise will not work if the windshield wipers are on.
Our VDC is not quick enough to completely correct for this, so while I think our cruise control may be safer than on an older vehicle, it is still not completely safe when road conditions are treacherous. When you think you may need to make quick adjustments to engine speed (e.g. when there are patches of ice), I would be careful about using cruise control. Unless of course it was at such a low speed that I don't think I'll need to slow down.

My cruise control continues to work even when the wipers are on (certainly on intermittent and low setting). Does it not work when the wipers are at high speed? That may be true because I know there have been a couple of times when I haven't been able to figure out why the cruise control refused to engage.
 

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05fxguy said:
MustGoFastR said:
plus our cruise will not work if the windshield wipers are on.
I think this only applies to ICC.
Hmm, possibly; I'll have to look into it.

As for use of cruise control in general, of course good judgement somes into play as well. It just wouldn't be too smart to use it in slipery conditions period.
 

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I use the cruise control all the time. I do experience sudden take off when hydroplaning in my '98 Dodge Status. The thing is when you're hydroplanning, the car actually slows down. So when the wheels finally get a grip of the road, the cruise control sees a sudden slow down and tries to speed up to compensate. That's when the car will seem to take off. It's how sensitive the cruise control is configured to restore the set speed. If it is set to be aggresive, then it will lurk when getting out of the hydroplaning. I haven't experienced that with the FX yet.
 
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