Whatever.I think you have some mis-conceptions about how the Onstar routing works......or doesn't work. I don't know about previous year models but the 2011 does use "true" GPS tracking. It's "accuracy" is similar to my stand alone GPS.
At an extra $100 per year......or even the discounted $50......I don't think it's a very good value, unless maybe you have lots of $$$ and your main concern is ease of use but it is not the cheesy service that you make it out to be.
Tower triangulation can be off as much as 1/4 mile in many cases and would be pretty much useless for routing purposes.......as it is for 911 locations.
I have a 2009 and a 2011, and no intention of pressing that blue button on either one. I don't care how accurate the system may be, the graphics SUCK.
I recently paid the $89 to Garmin for each of my Garmin GPS units (Zumo 550 and Nuvo 1450T) for lifetime maps. That's all I'll ever need or want. I want no subscriptions at those OnStar prices, thank you.