The number of new telematics systems from automakers has more than doubled in recent years. Systems such as OnStar provide car owners and their families with peace of mind in case of a crash or a catastrophic event such as a tornado or other disaster. But they're not just for emergencies. The systems also offer navigation services and conveniences like remote door unlocking, to name just a couple of features. Now, manufacturers are linking telematics systems to smartphone apps, giving owners remote control over some aspects of their vehicles.