Drivers find added features and lower prices with the latest models.

If you often travel to new places for work or pleasure, have trouble reading maps, or simply hate to ask for directions, you might consider a global positioning system (GPS) for your car. Once you input a destination, the system will plot a route, give spoken turn-by-turn directions, and display the route as you go. Most let you choose your routing preferences, including the shortest distance, the fastest time, or even routes with no toll roads. Some portable units even offer routing options for walkers and bicyclists to avoid highways and let pedestrians go against one-way traffic.

You can also quickly find a variety of points of interest, including gas stations, ATMs, hotels, tourist attractions, and more. Typically, you can search for a specific point of interest, search for ones that are near your current location, or look up ones in a different area. You can even choose a nearby restaurant by the type of food you wish to eat. Once you've located what you want, the system can calculate a route to get you there.

As more manufacturers continue to enter this competitive market, GPS prices are coming down and budget-priced units include features previously available only on more expensive models. For example, the Garmin nuvi 200, a CR Best Buy, comes with preloaded maps for 49 states and Puerto Rico, an internal battery, photo viewer, trip computer, calculator, and unit and currency converters, yet is priced at just $250. Higher-priced models can include text-to-speech capability, and such features as an MP3 player, and Bluetooth-phone compatibility, which allows you to call a phone number that's displayed on your GPS unit—handy for, say, making a reservation at a restaurant. services, such as traffic and weather reports, are also becoming more widely available, although they usually require a subscription.

Extra features aside, our testing has shown that GPS devices will typically get you to your destination, but not always by the most efficient route. There is no substitute for local knowledge of roads and traffic situations.

WHAT'S AVAILABLE

Buyers can get their directions from a wide variety of GPS devices, including built-in units in new cars, telematics systems, aftermarket portable or in-dash units, cell phones, PDAs, and laptop computers. All have advantages and disadvantages, and choosing the right one for you depends on your needs and budget.

Built-in systems. These are available as optional features when you buy a new car. They typically retail for about $2,000 when offered alone but are often bundled with other features, such as a backup camera or a high-end audio system, that can add another $1,000 or more. Built-in systems are usually the easiest to use, with large, clear screens that are optimally located in the dashboard and have generally intuitive controls. They are integrated nicely into the car, and some use touch-screen displays that make it easy to input destinations and navigate through menus. Some can also respond to voice commands, giving you the added safety of keeping your eyes on the road and hands on the wheel. And more systems are now providing real-time traffic reports, which can alert you to congested traffic, accidents, or road construction.

Automaker systems, however, are also the most expensive type of navigator system. Because they're built-in, you can't take them with you if you have more than one car or rent a car. Map updates must be purchased from the carmaker and can cost hundreds of dollars. Some systems prevent you from entering destinations while the car is moving. While this is intended to limit driver distraction, it also means a passenger can't program it unless the car is stopped. Finally, you won't be able to upgrade to new technology or features until you buy a new car. Similarly, if you're shopping for a used car, be aware that an earlier navigation system may have old technology and limited or outdated mapping.

Aftermarket in-dash systems. If you like the idea of an in-dash unit but aren't buying a new car or don't want a factory version, you might consider an aftermarket system. (The term "aftermarket" refers to components installed into a car after it's purchased.) They are typically packaged as part of a premium audio system. Like automaker systems, these can have a large, easy-to-read screen, and some can show real-time traffic conditions along your route, and play DVDs. In some systems, the motorized screen is retracted into the dash and out of sight until you want to use it, which keeps the dash uncluttered during normal driving. Aftermarket systems can cost as much as factory systems, and are best installed by a pro. Keep in mind that the audio systems in some vehicles are so integrated into the dash that it's difficult to install an aftermarket unit.

Telematics systems. These systems, which are only available on certain brands of cars, include OnStar from General Motors, Lexus Link, and TeleAid from Mercedes-Benz. They combine GPS and cellular technology, enabling drivers to contact a call center for help at the push of a button. All offer a variety of emergency and convenience services, some of which are free. Users to any of the three can opt for a navigation package that enables them to simply tell the service operator what address or point of interest they're looking for. Turn-by-turn verbal directions are then downloaded to the car to guide the driver to the destination, similar to a conventional GPS device.

In addition to verbal directions, some cars may also provide a basic graphic display showing each upcoming turn. But these systems typically don't provide a full map display.

Advantages include ease of use and being able to ask for directions even while driving. Another plus is that you don'thave to pay for updated mapping information. On the downside, you have to be in an area with good cell-phone coverage for the system to work. And the services can be expensive. GM sells more than 50 models available with OnStar either standard or as an option. Some of these include a free one-year trial period. After that, basic service starts at $199 a year and includes emergency service, remote unlocking, and stolen vehicle location. Adding the navigation capability costs another $100 per year. Buyers of some premium models get upgraded with free navigation for the first year.

Lexus buyers must first pay $900 for the LexusLink option, which includes one year of emergency help but not navigation. Adding navigation, which includes point-of-interest locations and the ability to call a friend, relative, or taxi if you can't drive, costs another $200 for the first year. Subsequent years cost $199 annually for the basic service or $399 with the navigation package.

Tele Aid is standard on most Mercedes-Benz models. Basic service includes roadside assistance and emergency help, for free the first year and $240 annually after that. Traffic information and turn-by-turn navigation are available for $450 annually.

Aftermarket portable systems. Today's portable units offer most of the features of built-in systems in a package you can carry with you. They can easily be moved from car to car, and their light weight and small size make them easy to pack in your luggage. With prices typically $250 to $700, portable units are much less expensive than built-ins. Features in portable units have been advancing in recent years. Real-time traffic reporting is available even on more-affordable units, and some now offer voice-command capability.

But portables have smaller screens than built-in automaker systems, which can make them harder to read at a quick glance. You also have to securely mount the device to prevent possible injury in an accident, make sure it's out of the way of possible air-bag deployment, and remember to hide or take it with you when you leave the car (theft of GPS units is a growing problem).

If the unit's battery loses its charge, you will also have to deal with a power cord running to a power outlet.

GPS-capable smart phones and PDAs. In recent years, a number of smart phones and PDA models have been introduced with integrated GPS receivers and mapping software. This allows them to function as a portable navigation device, with all of the functions and features of a dedicated GPS unit. While this eliminates the need to have two separate devices, smart phone and PDA screens tend to be smaller than those on dedicated GPS units, and they can be more difficult to use. With prices ranging from $400 to $600, they are also more expensive than basic portable units.

If you want navigation capabilities for your smart phone or PDA but don't have a model with an integrated receiver and software, you can often buy an add-on device starting at about $100. This usually consists of a Bluetooth receiver and software for the phone or PDA.

Cell-phone based navigation. Some cell-phone service carriers, including Sprint and Verizon, are now providing GPS navigation that can be accessed through compatible cell phones. Unlike GPS-capable smart phones and PDAs, these phones don't have internal mapping software or a POI database; they access the information wirelessly over the cell network. Menus and features are similar to other portable systems, including spoken and onscreen turn-by-turn directions, traffic info, and a point-of-interest menu. Advantages include the convenience of carrying one less device, continuously updated databases, and the ability to call ahead to a destination with the push of a button.

Moreover, the service's cost is typically about $10 per month, or it can be used for about $3 per day-handy if you need directions only occasionally.

The small size of some cell-phone screens, however, can make the map and directions hard to see. Smaller speakers compromise the audio quality of spoken directions, and small buttons are harder to manipulate than on larger devices. Not all phones are available with mounting systems to hold them. And the navigation function won't work if you don't have access to a cellular signal.

Map software and GPS receivers for computers. You can turn your laptop into a navigational device by buying an add-on GPS receiver and map program. These are available from companies such as DeLorme, Garmin, and Microsoft, starting at less than $100. While they provide functions similar to a dedicated GPS device, a laptop can be impractical to use while driving. Also, laptop screens can be difficult to see inside a car due to glare.

FEATURES THAT COUNT

Screen size. Built-in navigation systems typically have large screens (about 7 inches, measured diagonally) housed in the center of a car's dashboard. Portable systems we've tested have had screens from 2.5 to 5 inches. The smallest displays can be hard to see and can make for tedious programming with their small touch-screen buttons.

On the other hand, the largest portable units can be bulky to carry around and, when mounted to the windshield, can obstruct a driver's view of the road. With portables, we found that a 3.5-inch screen (or 4.3-inch wide screen) was a good compromise.

Map database. Most dedicated GPS devices now come with a comprehensive map of the entire United States already installed. Depending on the system, the map software resides on a solid-state memory card or an internal hard drive, although in our experience, it makes little difference in performance. Map updates for portable units can typically be downloaded over the Internet or from a DVD into your computer and then transferred to the GPS unit. Updates can be free or cost a fee, depending on the company. But unless you drive in an area with a lot of new construction, you probably won't need to update your maps more than every couple of years. Maps for other countries are also available for some systems.

If you're thinking of buying an older portable system, be aware that ones with limited internal memory initially showed only major U.S. highways. To get a more detailed map, individual regions have to be loaded from a PC—a tedious extra step and one that can seriously limit their usefulness if users forget to load the right map before starting a trip.

Spoken directions. This is a core feature of virtually all modern navigation systems. The better ones provide more precise directions, such as telling you to turn onto a specific street, highway or route number, rather than the more general “right turn ahead” or similar direction. This function, sometimes called text-to-speech, can be especially useful in urban driving, where streets can be close together. With good spoken directions, you don't have to look at the display as often, allowing you to keep your eyes on the road. Most systems allow you to choose from a variety of voices, with some now offering Spanish, Chinese and other languages. One company, Navtones, even provides celebrity voices for TomTom models.

Automatic rerouting. If you miss a turn, the system will automatically program a new route that will get you back on course. All systems provide this.

Predictive data entry. When typing an address or city name, the unit will highlight only letters that help complete a familiar name. For example, if you type in DEN, the system will highlight “V” as the next letter for Denver. As you type, a system might also display a list of matches from which you can choose. For instance, if you type “SAN,” your list of matches might include San Diego, San Francisco, Santa Barbara, etc. You can then choose from those or keep typing additional letters. We find this to be a helpful feature that speeds up entering an address.

Voice command. Some systems are now coming with voice-recognition software that allows you to perform major functions simply by speaking commands. Before buying, compare which functions can be controlled orally; the more, the better. In our experience, voice-command systems can be helpful. But they're not perfect; you might have to repeat commands at times or the system might misinterpret them. In our testing, this feature has often worked better in factory navigation devices than in portable units.

Detour feature. If you see traffic along your route, a “detour” button will find you an alternative route for a specific distance. That can be helpful in evaluating options before changing course.

Real-time traffic reports. Traffic information can provide warning of a problem or slow-moving traffic, enabling a driver to route around it. In some units, if traffic congestion is detected on your current route, the system will automatically ask if you want to find another route. The real-time data is transmitted through a cell-phone network, FM signal, or satellite radio signal. The service is currently available only in major metro areas, and the quality of information it provides varies from city to city. In our experience, we've found that the traffic information can be useful, but it can also be limited, inconsistent, and sometimes inaccurate. And to get it, some portable devices need a special receiver that costs up to $200. Higher-end models and automaker systems with this capability have a built-in receiver. For this service, you might also need to pay a monthly or annual fee.

Toll-road warning. Some systems can alert you to tolls on your chosen route and allow you to request a route that avoids them.

Mounts and mounting. Most portable systems use a large suction cup that affixes to the inside of the windshield. The bracket between the suction cup and the screen unit is typically a rigid arm, a ball-in-socket, or a flexible gooseneck. We recommend the rigid-arm type, because the ball-in-socket on some models might require ongoing adjustments and gooseneck mounts are apt to vibrate when the car is in motion.

Some companies offer a “bean bag” mount or an adhesive pad for mounting atop a dashboard. They are a cinch to use but a “bean bag” mount can slide and even fall off the dashboard during abrupt movements.

There are also third-party mounts available, but some of these are less secure than a suction-cup mount.

Two states, California and Minnesota, prohibit drivers from mounting devices to a windshield.

Power supply. All portable systems can be powered through a car's 12-volt socket, and most also have an internal rechargeable battery. An internal power supply lets you minimize the tangle of cords in the car. We found that these units typically operate for several hours on a charge, though testing showed significant variance among the latest models. Internal power allows you to practice using the system and to program destinations while out of the car, or to use the device as a handheld tool when walking or bicycling. An AC power adapter is sometimes included so the unit can be used and recharged indoors.

Bluetooth compatibility. This allows the user to make and receive hands-free telephone calls using the unit's internal speaker, microphone, and screen. It automatically quiets directions while the call is being made. It can also display the user's telephone book and show a caller's ID onscreen. You can also dial phone numbers of point-of-interest locations.

It requires a Bluetooth-compatible telephone.

MP3 player. The device can store and play preloaded audio files, through its speaker or through the car's audio system using a FM transmitter. The effectiveness of the transmitter, however, can vary by area; cities with a lot of radio stations around the frequency it's using can interfere with the transmitter's signal. The device can also be used for portable music away from the car. Most navigation units have SD card expansion slots for file storage.

Video player. This shows videos previously downloaded to the unit's hard drive or stored on a SD card. Using this feature normally disables navigation while the video is being shown.

Photo viewer. This allows a user to display loaded photos or photos stored on a SD card. They can be shown as single images or as a slideshow.

Foreign languages. In addition to English, many systems offer spoken and displayed directions in Spanish and French, and several have even more choices. Some TomTom models can provide spoken directions in more than 30 languages, but can't display them all on the screen. And some need to be downloaded from the TomTom Web site. For specific language needs, check with the device manufacturer for the latest out-of-the-box abilities and additional features that might be available by download.

Extra services. In addition to real-time traffic information, some systems are now offering such extras as weather information, gas prices near your car's location, and local movie titles and times.

HOW TO CHOOSE

Before you buy a GPS navigator, think about your typical driving conditions, how often you're in unfamiliar areas, and the features that are most important to you.

If considering a portable unit, we recommend focusing first on how well the system works for navigation. The highest-rated models we've tested make it especially easy to enter destinations and give the most helpful directions. Then consider what, if any, extra features you want.

What type of driving do you do? If most of your driving is spent commuting along the same route or running local errands on familiar roads, you might not get much use from a GPS device.

On the other hand, if you often encounter traffic congestion, a nav system can help you get around it by showing surrounding roads and plotting an alternative route. It also may be worth paying extra for real-time traffic information, which can warn you of traffic congestion, accidents, or road construction, and plot a route around it before you even get to the trouble area.

Will you be buying a new car? If so, check to see if a built-in system is available and how much it costs. These are typically easier to use and are nicely integrated into the car. But they are typically more expensive than portable systems, both initially and for subsequent map updates.

If you only need directions occasionally, a cell phone, smart phone, or PDA with navigation capability might meet your needs. With these, you don't have to pay for an expensive in-dash system or worry about carrying around a portable unit.

If you often travel in unfamiliar areas, you might find the ease of use of a dedicated navigation system a big plus. If you often fly to new places and rent vehicles, or if you own more than one car, a portable system might be the way to go—especially with prices for entry-level systems now below $200.

But if most of your driving is done in one car, you'd prefer not to have a unit mounted on the dash or windshield, and you're not on a tight budget, you might be happier with a built-in system.

What about extra features? A full-featured aftermarket model can effectively upgrade an older car with features like Bluetooth hands-free telephone capability, an MP3 player, an iPod connection, and a FM transmitter. If available, live traffic information, weather, and local gas prices can offer an increased measure of safety and convenience. But you may have to take on a subscription fee of about $60 a year.

What are your local laws? California and Minnesota prohibit drivers from installing any device on a windshield, the most common location for portable units, which typically attach with a suction cup. Check the laws in your area and the type of mounts available before you buy.

If you travel outside the United States, look for a portable system that offers maps for navigating in other countries. Most will function in the U.S. and Canada, but some models, such as the TomTom Go 920, will also work in Europe and other regions. Of the models we've tested, only the Magellan RoadMate 2000 was limited to just preloaded maps of the 48 contiguous states.

Built-in battery convenience. If using a portable unit, look for one with a built-in battery that will operate for at least four hours on a charge, especially if you want to use it for walking. While all systems include a plug for your car's 12-volt outlet, a built-in battery gives you the option of using the power port for another device, such as a cell phone, and it eliminates cord clutter.

A battery also enables you to enter a destination and plot a route before you enter the vehicle. Some models are also packaged with a traditional AC plug for in-home use and recharging. Others charge through a computer's USB port.

Size matters. If you choose a portable unit, size is important—especially if you frequently pack it in a suitcase. Some models are no bigger than a wallet and weigh less than 7 ounces, while others are as large as a paperback book and can weigh two pounds or more.

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