Of course, you must compare not only models from the same vendor but also models from competitors. While GPS devices share many similarities, their variations, as we discuss here, can help you make the best choice for your budget.
Screen size: Over the past several years, larger screens have been the trend for dashboard GPS units. Devices with a 4.3-inch screen have almost completely replaced ones with 3.5-inch screens. Any devices with 3.5-inch screens that you can still find are typically entry-level models, often with a limited feature set. Now, 4.3-inch-screen units are being replaced by ones with even larger screens. Devices in Magellan's RoadMate 3000 series, for example, all feature 4.7-inch screens, and the RoadMate 5000 series offers 5 inches. Similarly, TomTom's chart-topping XXL products (such as the ), as well as the new , have 5-inch screens. And if you want a portable with a truly big display, Magellan's has 7 inches.
Live traffic alerts: Among Garmin devices, those with a T in the model name include traffic alerts. In Magellan's lineup, all of the 2000, 3000, 5000, and 9000 series of RoadMate units include traffic, too. In both the Garmin and Magellan lines, the traffic feature is ad-supported--you don't have to subscribe to the service, but you will get occasional pop-up ads. TomTom's alerts, found in models with T in the name, are also subscription-free, but sans advertising.
Maps: Manufacturers have learned that consumers want to update their maps, and these days some models include lifetime map updates, generally available quarterly. Garmin and Magellan RoadMate models with this update feature have LM in the model name; TomTom models have M. Magellan's MU models receive a single map update during the life of the product.
The included map set is a key consideration, as well. Maps can cover not only the United States but also Canada, Mexico, and Puerto Rico. Some high-end models may have maps of Europe. Less-expensive units typically have less map coverage. If maps of Canada or Mexico are important to you, check the included map set for the device you are considering.