You are assuming I carry any device Google is capable of tracking on my person. If a car comes with Google Maps built in, it is no longer a car I can consider for purchase.
I'm actually super impressed with the recent progress that the Android OpenStreetMap client has made. In the past six months or so it's gone from virtually useless to being a full Google Maps replacement (at least for my use cases).
I found the actual map quality quite lacking, unfortunately. Your mileage may vary by location, of course. I had been testing using OSM for a project to get some data, and MapQuest both had the OSM data and their own proprietary data. I compared the two and it was really painful to try and work with OSM's data.