Well It passes my first test. The dead reckoning feature of my BMW zumo 550 works, well maybe. It appears to work with my '08 R1200GS, but I am going to test it further. According to my dealer, this feature does not work with all BMW motorcycles. If your not sure what dead-reckoning is, I've described the feature below. The test I conducted is also described below. Dead Reckoning The dead-reckoning feature is enabled by use of a CAN-bus connection through the BMW power cable supplied with the BMW zumo 550. When the zumo looses satellite reception, in tunnels, canyons, streets flanked by tall buildings, and such, it takes speed data gathered through its CAN-bus connection and heading data from its internal compass to produce continued position tracking on its display. Of course, dead reckoning is not as accurate as the position tracking provided when the zumo is receiving good satellite signals, but it allows the GPS to continue plotting your position even with temporary satellite signal loss. A a result, you have a better chance of making the correct turn half way through that "urban canyon" of a city street. The Test To test the capability on my bike I took a detour into a multi-level parking structure, since there are no nearby tunnels or canyons. I drove around one floor of the structure then dropped down one floor before making an exit. When I have done this in our car with our nuvi 760 or Vista C, they have lost satellite reception and stopped tracking my position. My BMW zumo/R1200GS setup continued to track a position. When I download the track from the zumo to RoadTrip, I found a complete, uninterrupted track of the trip, including the nearly two loops in the parking garage. Now I will look for a long tunnel and test it again.