Advice For Motorists Who Have Cruise Control On Their Vehicle.

[Stargazer]

A 36 year old female had an accident several weeks ago. It was raining, though not excessively when her car suddenly began to hydro-plane 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 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, your car will begin to hydro-plane when the tyres lose contact with the road, and your car will accelerate to a higher rate of speed making you take off like an aeroplane. She told the patrolman that was exactly what had occurred. The patrolman said this warning should be listed, on the driver's seat sun-visor - NEVER USETHE CRUISE CONTROL WHEN THE ROAD 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 road is dry.

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

NOTE: Some vehicles (like the Toyota Sienna Limited XLE) will not allow you to set the cruise control when the windshield wipers are on. Even if you send this to 15 people and only one of them doesn't know about it, it's still worth it. You may have saved a life.

[bhg481]

Same as your other two links - rubbish. Cruise effectively keeps the driving wheels rotating at a fixed speed, not the car at a constant speed, which will not be the same if you lose traction. If you lose traction there is no reason for the cruise control to increase the engine speed.

[THECORBYLOON]

According to Snopes, this one is TRUE, http://www.snopes.com/autos/techno/wetroad.asp

[bhg481]

Please explain how and why the car will increase in speed when traction has been lost. The speed of rotation of the wheels wil not increase (why should it?), so why will the car go faster and "take off"?
I have been using cruise control for 15 years now; no-one but an idiot would use it in icy conditions, nor should anyone drive in heavy rain at a speed which might produce hydroplaning, with or without criuse control.

[Old_Geezer]

Reading Snopes it agrees that there is an issue but not that the vehicle takes off like a rocket/aeroplane. It's about needing to react quickly and not needing to turn off the cruise control first.

In my view it sounds like a design flaw in cruise controls not recognising the situation and reacting appropriately. It's basically telling me that cruise control can only ever be used in the UK during our week of summer. Perhaps the secret is not to set the speed to one high enough to aquaplane in wet conditions: but difficult to decide on when on motorways where they're most used.

[bhg481]

There is no way the car can speed up if traction has been lost due to aquaplaning (or any other reason).

[THECORBYLOON]

Is the basic message, never drive in adverse conditions using cruise control, correct?

[bhg481]

I think I largely agree with that, THECORBYLOON; in really adverse conditions you need to be fully in control of your car. I'm not disagreeing with not using cruise in adverse conditions, I'm disageeing with the logic of the car speeding up.

[mikeB2]

Cruise control maintains a constant driving wheel speed. If the car starts to hydroplane the wheel speed will stay the same. As others have said, you should never get into a hydroplaning situation. Modern tyres are very good at displacing surface water, but they get less good as the tread depth reduces. The moral is don't drive at 70mph on tyres with minimum tread depth (1.6mm). CC will not make any difference. I use mine frequently. It's very good at making sure you don't get caught speeding in a contraflow.

[TheChair]

Most modern cars with CC, also have ABS and Traction Control.

[MantaRay]

For the non-technically minded the cruise control keeps the throttle open at the very moment that a manually driven throttle would be lifted instinctively by the driver.