So you would be locked into AT&T for the life of the vehicle
Unfortunate that the telcos continue to own the FCC. With each telco providing a unique 4G implementation users cannot go from one to a competitor without buying a new cell phone or smartphone or Mifi or USB modem. They will also need to buy a telco specific signal booster (and starting in 2014 get the written permission of the ISP to use it) as well.
To buy a GM product and be locked into AT&T is hardly a positive reason to buy one of their cars. With AT&T wireless service I was overcharged 6 out of the first 7 months of my contract. Each time it took an hour to get the overcharges corrected and I finally cancelled my contract after the seventh occurence.
GM should be providing a signal booster and efficient 4G antenna and a router funtion if it really want to benefit its customers. Instead its engineers took the easy route and let AT&T's people do the design work.
Just like Sirius satellite radio where one has to buy a package and subsidize all the right wing political and religious nut jobs on the radio with your subscription dollars. The Reagan legacy lives on.