[stuartcr]

Just don't pay for the OnStar service. As for the GPS devices in your cell phone, disconnect the battery except when you want to make a call, or use an old phone with no GPS.

[ovrtaxt]

Even if you don't pay, the unit is still active. It can always be used for emergency, and they can still track your location. It's ALWAYS on. (unless you rip it out of your trunk...)

If they can unlock or lock your doors remotely, I'll bet they can also shut your engine off, or manipulate anything else controlled by the car's computer.