I received the following e-mail today, and it made me wonder how many have gotten it and actually believe it to be true:

Driving in the Rain
I wonder how many people know about this ~   
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 excessively, 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 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 when your car begins to hydroplane and your tires lose contact with the pavement, your car will accelerate to a higher rate of speed making you take off like an airplane.   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 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. 

NOTE: Some vehicles (like the Toyota Sienna Limited XLE) will not allow you to set the cruise control when the windshield wipers are on.  

If you send this to 15 people and only one of them doesn’t know about this, then it was all worth it.  You might have saved a life.

First, the basic lesson of the note is true - you should not use your cruise control in slippery or icy conditions.  It reduces your reaction time to changing and hazardous conditions.  Also, to disengage cruise control you press the brake pedal, which is the WORST REACTION if your car begins to slip in the rain (it’s actually a bad move on slippery roads period). Pressing the brake when your wheels begin to lose traction will cause you to lose control.  If that happened to the lady in the story (assuming it’s not a complete myth), it may have felt like “flying”, but it was just an uncontrolled spin/skid.

The rest of the note is utterly false.  Your car CANNOT speed up if it is hydroplaning.  Hydroplaning occurs when the tires are riding on the plane of water and not on the road surface.  In order for your vehicle to gain speed, the tires must be in contact with the road surface.  The car might “think” it is speeding up, as the tires might well begin to gain speed as they rotate faster in a hydroplane situation, but the vehicle will not be gaining speed.

Even if the car were to suddenly gain speed, your car cannot “literally” fly through the air - unless you drive off a cliff or up a ramp a la Evel Knievel.  I consulted an expert in aerodynamics and jet engine design, who has multiple degrees in aerospace engineering.  He said (and this is an actual quote), “That’s a funny email…Duhhh… cars can’t take off like an airplane.  Should be self-explanatory.  No wings to generate lift, too heavy, etc.  And again, the tires aren’t grabbing the road this scenario (slippery), so how can you accelerate??  The only force acting on the car is air resistance, which is slowing it down.”

Tires. Most of us never think much about them, unless something goes wrong. We know that we should check the air pressure, making sure they are properly inflated and we know that tires without much tread (”bald”) are dangerous and should be replaced. Some of us even know the trick of putting a penny in the tread with Lincoln’s head down to check how much tread we really have.

But, did you know that tires can go bad sitting on the tire store shelf? A “new” tire that has never been used can go bad like last week’s milk. This is very likely nothing to worry about for the vast majority of tires, especially on a new car or truck. However, it doesn’t hurt to make yourself aware. And it might hurt to not be.

Watch the clip from ABC News for the full story. Probably over sensationalized, but worth watching:

http://abcnews.go.com/Video/playerIndex?id=4826897