Ring! "Hello?" Car: "It's your car." You: "My what?" Car: "I've just been stolen and have alerted the authorities." Okay, that's a call nobody wants, but GM has just added a feature to its OnStar security system that does exactly that, called "theft alarm notification." It works with appropriately equipped OnStar vehicles to contact you via text, email or phone if a bad guy activates the alarm on your GM vehicle. The feature is an add-on to GM's existing security system, which already lets OnStar advisers contact the police, track your vehicle and even slow it down or shut it off if it's safe to do so.
Since it's probably not a good idea to chase after car-nappers yourself, we presume that the theft notification system is more to just keep you in the loop than anything else, or at least help you ensure the relevant authorities are contacted. Similar features are available on aftermarket alarm systems, but GM is one of the first companies to factory install it into vehicles. It'll be available this summer to owners of most GM cars made after 2014, but if you're not sure you qualify, check this list.