Monitoring speed maybe, for the purpose of enfocing the speed limit makes sense. Some European communities have cameras that record the times you pass certain markers, then figure out how fast you went. A few days later, a ticket appears in the mail. I think the Germans are notorious for that. That would suck, but I can see the US headed that way.
But remotely shutting down a vehicle? Sounds dangerous. On-star can already unlock doors remotely. Hopefully you dont piss off an On-star employee huh?
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I USED TO HAVE an 85 Camaro 305 4bbl, 90 Firebird V6, 97 Firebird V6 (10 speakers!). Despite the two family vehicles, 3 kids, wife and mortgage, I can finally realize the dream - 88 TA almost all stock... for now.
http://www.cardomain.com/id/untameddave
Wanted this -

, but ended up with this -

for free. Can't argue with free.