The myriad automotive GPS receivers available today make it difficult to find the right model. Here are a few things to look for when shopping:
- Screen size: make sure the screen is large enough to see and read from your windshield or wherever you mount it.
- Maps: make sure the local, regional, national, and international maps you need are pre-loaded or available for purchase.
- Map updates: check how often maps are made available for download, and what they cost. Most give you one free update when you buy it. TomTom lets users make map corrections on certain models, then upload them to TomTom for sharing via its peer-to-peer Map Share service.
- Spoken directions/text-to-speech: GPS receivers come in varying levels of talkativeness. Some simply display directions and street names, others speak directions and leave you to read the street name (e.g., "left turn ahead"), and others speak even street names (e.g., "left turn ahead, Maple Street").
- Traffic service: enables your GPS receiver to use traffic congestion and accident information in planning routes.
- Bluetooth: allows you to wirelessly connect the GPS receiver to your phone, to make and receive calls through the GPS receiver.
- FM transmitter: speaks through your car's radio system, instead of the small built-in speaker.
- Itinerary management: some receivers let you create an itinerary (basically a list of locations to visit in a certain order). As you visit each stop on your itinerary, the receiver directs you to the next one. For receivers without this, you need to add each stop to your favorites and manually select each as your next destination.
- Address storing: GPS receivers use different methods for storing the addresses you enter. TomTom converts street addresses to coordinates, which means when you arrive at a row of houses and it says "you have reached your destination", it's up to you to remember which house number you were looking for. Garmin stores the original street address, so it will display the house number when you arrive. I don't know how other manufacturers handle this, but I much prefer Garmin's method.