OnStar service. The new feature lets subscribers track the exact location of vehicles at any time via an online map. Subscribers can also set up a text message alert to keep on top of the car's location. There's certainly potential for the feature as a safety tool, but it's also no doubt a long awaited addition for overbearing parents everywhere. The service is beginning life as an invitation-only pilot program that includes around 10,000 OnStar subscribers.