Price

• Decide first approximately how much you want to spend on your GPS unit. Because so many devices are on the market, choosing a price bracket ahead of time can help narrow your search. Most manufacturers offer entry-level units for around $100, with prices ascending to upwards of $1,000. In-dash systems are available, but remember to take into account the cost of installation when deciding how much you'd like to spend on the unit.
  
  

Features

• Address-to-address routing is of primary importance for automobile GPS units because it gives you the ability to enter a starting address and then get detailed directions to your ending address. As of 2010, most automobile GPS devices include this feature. After determining whether your unit has this feature, compare its text-to-speech functionality, audible voice navigation (where a voice reads the directions aloud) and the number of waypoints (or points of interest) that can be inputted into the system. Other features to consider include traffic routing (which adjusts directions based on the volume of traffic along the route) and Bluetooth functionality.
  
  

Screen and Function

• The size and clarity of the screen are of great importance when comparing automobile GPS units. Most dash-mountable screens measure between 3 and 5 inches diagonally from one corner to the other. Bigger screens can improve your ability to read the screen while driving, but if the screen is too big and mounting room is limited, a screen can begin to obstruct your view of the road. When comparing GPS units, test that the screen is easy to read and that its touchscreen and menu system are easy to see and function in a way that feels natural to you.
  
  

Considerations

• Check the warranty provided by the manufacturer. As with any electronic device, failure can occur for a number of reasons outside of your control. Also, read the manufacturer's policy on map updates. Most manufacturers will allow you to connect your device to the Internet one time and download the most up-to-date maps. Users are often charged for subsequent updates.