Mine has been so poor that I now use my Garmin on long trips, rather than the built-in BMW Nav.

On paved state highways in Utah, it consistently computed my estimate arrival time and travel time assuming an average speed between 20-25 mph.

Using the find function, find something in Van Horn, TX. Click to route yourself there, and you will find it now has the same street address, but says you are going to Kent, Tx, another town about 37 miles away. So when you are traveling, the question becomes is it really in Van Horn or in Kent?

In Idaho it told me to turn left on a non-existent road on a remote highway location, where there was no road in either direction for miles.

Here's a specific I wrote down. Find a shell station at exit 193 going east on I-40 and tell it to route you to it. It will not tell you to take the appropriate exit, because the map places it under the crossover road between the east and westbound interstate lanes. So you miss your fuel stop.

Over the past year on trips in the West there have been literally dozens of instances like this.