Traffic and maps services
The TM at the end of the model name stands for Traffic and Maps, as in lifetime traffic data and map updates.
Traffic data comes over the RDS-TMC band through a traffic receiver built into the 12-volt power adapter. Interestingly, TomTom has made the jump to a Micro-USB connection for the Via series' combo traffic receiver and power adapter, so in a pinch you could power the PND with most smartphone chargers and vice versa. Traffic data arrives in the form of incident icons and flow overlays on the map screens, in the trip overview screen, and in the Traffic submenu under the Services menu.
Unlike TomTom's own HD Traffic service that comes as part of its Live Services suite, the basic traffic service that is delivered to the 1535 TM usually only includes flow data for highways and major surface roads. To fill in the blanks in this coverage the Via series can take advantage of TomTom's IQ Routes algorithms, which take historical, time-sensitive flow data into account when routing. This data is harvested anonymously from TomTom users who opt in for this feature.
Map updates are downloaded quarterly to a desktop via the MyTomTom software and synced with the unit via the included Micro-USB cable.
Between the year's four major map updates, you can download smaller map updates from TomTom's Map Share, which pushes user-generated minor corrections for smaller tweaks to street names, traffic direction, closed streets, turn restrictions, speed limits, or missing or new POIs. You can also make and submit your own map corrections for upload to TomTom's servers and to other users upon approval.
Routing and navigation
On the road, the TomTom performed well. We noticed that traffic data actually seemed to have an effect on the routes chosen by the Via 1535's routing algorithms. For example, routing a trip to our favorite burger joint in the next town in the afternoon had us exiting the interstate much later in the trip than the same route planned at lunchtime the next day, when we were prompted to exit the highway early and make the last leg of the trip on surface roads.
Turn-by-turn instructions were clear and voice prompts were given enough in advance that we were able to make the turns without rushing. Particularly useful was the advanced lane guidance feature that graphically marked the lanes of major highways that were valid for our chosen route, which kept us from unnecessarily moving over two or three lanes when one would do.
Satellite reception was also good with accurate positioning, even among downtown San Francisco's tall buildings.
At this point, we've tried out a few devices with TomTom's new interface. We're over the learning curve for the most part, but we still find ourselves fumbling with the dual maps. That's not to say that the interface is bad, because it's not, and it represents a huge improvement over TomTom's older interface. It is still a bit more complex than we're comfortable fiddling with at highway speeds, but if you stick with the basic and voice command functions while in motion and leave the more advanced features alone until parked, we think you'll probably like it.
Overall, the TomTom Via 1535 TM proved to be an exceedingly competent GPS navigator, and with the added value of lifetime maps and traffic updates, we think that it will continue to be useful long after purchase. Also, Bluetooth hands-free calling and voice command enhance driver safety, making it easier to keep hands and eyes on the road.