Portable Navigation Features
Features in Portable GPS navigation systems
These are things to consider when choosing a navigation system with the right balance of ease of use, performance, safety, and the features you're looking for
Screen size. Built-in navigation systems typically have large screens (7 inches, measured diagonally) housed in the center of a car's dashboard. Portable systems generally mount above the dash, somewhat closer to the driver, where it's easier to see their smaller screens. The portables in this group had screens ranging from 3.4 to 5 inches. Previously tested units had screens as small as 2.5 inches, but we found the smallest displays can be harder to see and can make for tedious programming with their small touch-screen buttons. The largest units can obstruct a driver's view of the road, in addition to being bulky to carry around. We found the common 3.5-inch screen to be a good compromise.
Map database. Most systems, including all in this group, now come with a comprehensive map of the entire United States already installed. Previously tested systems with limited internal memory initially showed only major U.S. highways. (To get a more detailed map, regions had to be loaded from a PC--a tedious extra step and one that can render those systems useless if users forget to load the right map before starting a trip.) 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 to the system's performance.
Dynamic database gray-out letters. When typing an address, the unit will gray out letters that are not possible to complete a word; for example, if you typed in XYLOPHO, the system would grey out everything but N (because that would be the next letter in the word xylophone) and whatever other few letters might complete the word. We find this to be a helpful feature.
Real-time traffic reports. Live traffic information tied to a navigation system can enable a driver to route around a problem or slow-moving traffic. The real-time data is available to subscribers through a cell-phone network, FM signal, or satellite radio. But the service is currently available only in some cities. These devices typically need a special receiver that costs up to $200 to provide traffic information, or you have to buy an upgraded model that includes a receiver. For this service, you might also need to pay a monthly or annual fee.
Detour feature. If you see traffic building up ahead, a "detour" button will find you a parallel route for a specific distance. That can be helpful in evaluating options before changing course.
Toll-road warning. Some systems can alert you to toll roads on your chosen route and often allow you to request a route that avoids tolls.
Mounts and mounting. Most portable systems use a large suction cup that fixes them to the inside of the windshield. The bracket between the suction cup and the screen unit is typically either an angled rigid arm, a ball-in-socket, or a flexible gooseneck. We recommend the rigid-arm type, because the ball-in-socket might require ongoing adjustments and gooseneck mounts are apt to vibrate when the car is in motion. A "bean bag" mount simply sits on the dashboard. It's a cinch to use but can slide and even fall off the dashboard during abrupt movements. Two states, California and Minnesota, prohibit drivers from mounting devices to the windshield.
Power supply. All portable systems can be powered through a car's 12-volt socket, and many also have an internal rechargeable battery. An internal power supply lets you minimize a tangle of cords in the car. We found these units typically operate for several hours on a charge, although testing revealed significant variance among the latest models. Internal power also allows you to practice using the system and program driving destinations while you are away from the car, or to use the device as a hand-held tool when traveling, walking, or bicycling. An AC power adapter is sometimes included with the systems, allowing the device to be used and recharged indoors.
Bluetooth compatibility. Allows the user to make and receive hands-free telephone calls using the unit's internal speaker, microphone, and screen. Automatically quiets directions while call is being made. Can display user's telephone book, and shows caller ID on-screen. Can also dial phone numbers of point of interest locations. Requires a Bluetooth-compatible telephone.
MP3 player. The device can store and play pre-loaded audio files, either through its speaker or through the car stereo using an FM transmitter. It can be used as a portable music device away from the car. File capacity varies by unit. Most navigation units have SD card expansion slots for file storage.
Video Player. Shows videos previously downloaded to unit's hard drive or stored on an SD card. Using this feature normally disables navigation while the video is being shown.
Photo viewer. Allows user to display previously loaded photos or photos stored on an SD card, as a single image or as slide shows.
Foreign Languages. Many units offer spoken and displayed directions in Spanish and French in addition to English, 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, it is recommended that you check with the device manufacturer for the latest out-of-the-box abilities, and additional language features that might be available by download.