GPS Devices have an increasing number of features and options that can be quite overwhelming when you’re trying to decide on what unit to buy.

Here are some of the most important features you should look out for:

Maps: When you buy an in-car GPS in the United States, you generally receive street maps for the whole country, and sometimes for the entire continent. You can also purchase maps for other countries as needed. Since there are only two or three primary sources for most of the digital map data, there is not too much difference between the maps shown on different models.

There is more variation with handheld units. There are some that cannot show maps at all, and only give you your longitude and latitude. They also display a trail or track of your previous coordinates to show where you have come from. More sophisticated models can store maps of streets and terrains, and a smaller number will let you download satellite images. Remember that most handheld units have small screens, which can make it tricky to read a map.

3D map view: GPS units for the car tend to show maps in 3D map view (bird’s-eye view). The map is updated constantly as you drive along, so that you always see your current location and the surrounding landscape. If your GPS only offers 2D views, the map will look exactly like a piece of a normal printed map. A 3D view shows you the area around you as seen from a height of two hundred feet or so. This produces a map that is easy to read when you are driving.

Turn-by-turn directions: This is the most useful feature of an in-car GPS. Finding your way to your destination is simple with a unit that gives you both visual and spoken directions about where to turn left or right, or get on or off the freeway. Text-to-speech functionality, which pronounces street names, is included in most devices these days. For instance, the unit can tell you to turn right in 500 feet onto Walnut Avenue, rather than just turn right in 500 feet. While text-to-speech was previously only available on expensive models, you can now find it on many popular-priced GPS units too. A few of the most basic devices don’t have text-to-speech functions, but for most motorists it’s a must-have that is worth paying for.

In most GPS models, the spoken road directions are delivered though the on-board speaker. Some, however, have a short-range FM transmitter that links to your car radio, which makes it easier to hear the instructions over the noise of the engine.

The majority have an on-screen keyboard where you touch the screen to spell out the address – and most have an autofill function to save time – then press Go. Make sure you set up your journey before heading off, though – don’t try to use the keyboard while driving! Certain new models have voice-recognition features that let you speak your instructions out loud. You can make changes while driving, but it is not always 100% accurate, so don’t put all your trust in it!

After a few seconds, your GPS will display the calculated route on the electronic map. It is important when you are at the wheel that you receive your directions in a clear and timely fashion. Your GPS should be able to give you route instructions at an appropriate time – neither too early nor too late – to ensure that you can drive as safely and calmly as possible.

Display size and type: GPS devices for automotive use can have screens ranging from 3.5 inches to 7 inches diagonally. A smaller screen can actually work perfectly well, as long as it is well designed and comes with good audio features. Bear in mind, too, that a larger display costs significantly more than a small or medium-sized one. You can do much more with a big screen, though, and you might find it worth spending extra to get larger maps, more space for travel information (speed, direction, street labels) and a less cramped on-screen keyboard. Handheld GPS units normally have small displays, which tend not to be suitable for touch-screen controls. Therefore, the controls on handheld devices can often be quite convoluted.

POIs (points-of-interest): This is an onboard database of locations and businesses such as gas stations, motels, fast-food outlets, parks and local attractions. Some POI lists feature phone numbers as well as names and addresses. A typical vehicle GPS will have several million POIs on record. However, POI lists are usually less up-to-date than street maps since businesses tend to change or move quite frequently.

Real-time traffic updates: You can receive real-time traffic information on many GPS models, via either an FM transmitter or a wireless signal. If your GPS doesn’t have an inbuilt receiver for these services, you might be able to get one as an add-on. There might be a fee for subscribing to the traffic reports. Your live maps will show traffic jams and delays due to road works anyway, so that you can save time by selecting a different route. There are also GPS units that automatically change your route based on traffic updates.

Lane assistance & realistic road views: If your route is completely new to you, even clear spoken directions can be confusing at times. A useful feature that is appearing on more GPS units now is lane assistance, which lets you know which lane to drive in ahead of upcoming turns or highway exits. There are also units that display simulated images of the road, down to the street signs. This can be particularly handy when you are approaching confusing intersections. To confirm that you are on the right street, you only need to take a quick look at the display.

Channels: The number of channels corresponds to the number of satellite signals the device can receive at any one time. Cheaper models generally have 12 channels, and more sophisticated units as many as 24. In broad terms, a higher number of channels makes the GPS device more accurate.

Media card slots: There are two different ways for GPS units to store their mapping and POI information. Your device will either use a built-in hard drive or a flash memory card such as a microSD card. Each method has its own advantages: media cards are longer-lasting, while a hard drive allows for faster route calculation and POI searches. A GPS with a hard drive doesn’t necessarily need a media card slot, but many models have one anyway. This makes it easy to update map data and back up addresses. It also means you can use the multimedia features, like music and video players, that come with some top-end models.

Waypoints: You can save waypoints, which are the latitude and longitude of specific locations, in your GPS unit’s memory. If you want to hike up a trail, for example, just hit the waypoint record key before you leave the car, and you will be able to find your way back without any problem. Waypoints are vital for those using handheld units, but are seldom used in the car. As you would expect, entry-level devices have only basic waypoint functions and little storage capacity. High-end units, in contrast, let you store hundreds of waypoints, label them as you want, and manage them within the database.

Tracks: Handheld devices generally have a tracks function, which records and displays a breadcrumb trail as you walk or drive along your route, so that you can easily trace your way back. On certain models you can download a track to your computer, superimpose it onto a topographic map and print out the result. If you want to store many tracks and name them yourself, you will need a top-of-the-line GPS, while a cheaper model should suffice for someone who only uses this feature occasionally.

GPS Buying Tips:

• Introduction
• Some Basic Facts
• What is GPS & How Does IT Work?
• The Most Important Features
• Other Features You Might Want