It might be tempting to "pimp your ride" with the latest auto gadgets. But some can be dangerous -- even deadly.

THOUSANDS OF AUTO-GADGET manufacturers converged on Las Vegas this week for the annual Specialty Equipment Market Association (SEMA) show. From what we hear in the pits, the confab was bigger than ever.

Demand for aftermarket auto gear -- everything from fancy rims to sophisticated navigation systems -- is soaring. Thanks to the popularity of television shows like MTV's "Pimp My Ride" and hip-hop videos, the specialty-equipment business has grown into a $29 billion-a-year industry, according to SEMA.

But while these gadgets can be fun to look at, they aren't necessarily safe. Some, in fact, can be deadly. The more things drivers add to the insides of their cars, the more tempted they are to take their eyes off the road. Driver distraction accounts for 25% of all reported car crashes, according to the National Highway Traffic Safety Administration.

So before you customize your ride, consider the dangers that come with even the most popular and mundane accessories.

1. Cell Phone
Talking on a cell phone while driving is more dangerous than most people realize -- even when a headset is used. According to a University of Rhode Island study, conversing on a telephone causes drivers to experience decreased alertness to their surroundings.

Research shows that the cognitive processes required to carry on a telephone conversation are different from those required to carry on an in-person conversation. Telephone talking results in tunnel vision -- which for a person driving a car is obviously quite dangerous. That's why laws that merely restrict the use of handheld cell phones don't do enough to protect consumers, says Judie Stone, president of Advocates for Highway and Auto Safety, a Washington, D.C., lobbying group. The fact is, no cell phone mechanism is safe for a person who's driving.

2. Navigational Systems
For those who weren't blessed with an innate sense of direction, an onboard navigational system might seem like a godsend. But some systems are better than others. The most dangerous ones are the small handheld devices or software programs used in laptop computers, warns David Champion, director of automobile testing at Consumer Reports. These are difficult to see, and tend to take the driver's eye far from the road.

A better alternative is an internal system located right on the car's dashboard. But even these must be used properly. Champion recommends inputting your destination before beginning to drive. Then, resist the temptation to look at the digital map while driving. At the risk of sounding obvious, Champion warns against typing in an address while operating a vehicle.

3. DVD Players
Believe it or not, some of the more sophisticated in-dash navigational systems can now play DVDs -- even while the car is speeding down the interstate. Think no one would try to do this? In 2002, an Alaska man was allegedly watching an in-dash movie when he swerved into oncoming traffic, killing two people. (He wasn't convicted of a crime.)

4. MP3 Players and Satellite Radio
Most people agree that listening to the radio while driving is safe. But the popularity of satellite radio and MP3 players is making this mundane activity a bit more distracting. Satellite systems and MP3 players come with a small digital screen that list song and artist names. The longer the name, the more time a driver could spend looking at the radio rather than the road. (Just imagine how dangerous the Fiona Apple album "When the Pawn Hits the Conflicts He Thinks Like a King..." could be.) And if a driver wanted to find a specific song on an MP3 player, he or she could scroll through hundreds of tunes before finding it, warns Karl Brauer, editor in chief of Edmunds.com. In the old days, all people had to do was turn a knob on the radio, a much more intuitive and less distracting activity, he says.

5. Car Office
You've heard of the home office. Now, imagine it on wheels. Yes, more and more Americans are conducting business in the cars these days. Thanks to wireless technology, a car office is easy to set up. The concept is appealing to some: Why waste all that time commuting to work when work can be done in transit? But even a task as simple as checking a BlackBerry for e-mails while you're idling at a traffic light takes your focus off the road.

Using any one of these gadgets in isolation might be manageable. But Americans are multitaskers at heart. It isn't difficult to imagine someone talking on the phone, checking e-mail and scrolling through his music library all while driving 65 miles per hour. Such a combination would be a road map for disaster.