Like the Times, we've been comparing the GPS traffic features of our Garmin device (1490T) and our Google navigation app on our mobile phone (Sprint Samsung Epic 4G).
The phone produces maps with red lines on them which indicate slow traffic. We need to know, coming from Queens, if the Cross Bronx is backed up before we get to the turn-off to the Bruckner. We have a shortcut via the Bruckner that will save us up to half an hour when the Cross Bronx is really bad.
In the past few months, nine out of ten times, the Google navigation app has been accurate in indicating bad traffic on that one road. We do have to scroll and squint to see it. But if the red line is there on the Cross Bronx, we turn off before getting stuck in it. If it is green, we take a chance on the Cross Bronx.
We just upgraded to a Garmin GPS with traffic reporting as a feature via an FM antenna in the power cord. It's been disappointing in several ways. By the time it indicates that there is a tie-up, most of the time, we are in it. And for that feature, we joke that we already have a wife to serve (when she is in the car) to announce that we are in traffic.
The positive Garmin feature is that when set for a trip destination, the GPS will tell us in a little icon how many minutes traffic will delay us. But the bad side to that is that it is mostly wrong. To be fair, the Cross Bronx may be one of the most difficult and complex routes in the US to predict. It by far is one of the worst roads. Without traffic, it is less than 10 minutes from the Throgs Neck to the GWB. With bad traffic it can take, on the worst day, over an hour.
For a more detailed comparison of how these systems compare in LA, see the Times article, When an Android Phone Becomes a GPS Device, By ERIC A. TAUB.