OnStar has expanded from its beginnings as a crash-monitoring and emergency services system to allowing subscribers to keep track of a vehicle when it’s stolen and find a car in a crowded parking lot using a smartphone application. And now it will let them keep tabs on their kids or loved ones driving the car.

OnStar’s new Family Link, an optional service the company debuted last year in a pilot program, includes two features. The first is Vehicle Locate, with which subscribers can view a map with the car's location by logging on to a Family Link website. With the second, Vehicle Location Alert, subscribers can set up to have an email or text message delivered to indicate the location of the vehicle. The types of alerts can be selected by the day, time and frequency.

OnStar will launch the service in mid-April and offer it “to select OnStar subscribers who will receive an invitation to purchase and sign up for Family Link.” More subscribers will receive an invitation in June, and the service will roll out nationally through 2012.

Only OnStar subscribers with the correct name and password can access the Family Link website or the vehicle alerts. To use Vehicle Locate, subscribers log on to the Family Link website and click on Locate on a Vehicles tab. An icon on the map shows the location of the vehicle, and other location info hovers over the vehicle icon.

Setting up a Location Alert is a similar process. Subscribers log on to the Family Link website and click on Add Alert on an Alerts tab. The subscriber can select a day of week and time to receive alerts and how they would like to be notified, by text, email or both. The address the vehicle is closest to and the date and time are included in Location Alerts.

Family Link includes both features for $3.99 a month, and OnStar subscribers can add it a la carte to their existing service. It’s a small price to pay for the peace of mind of knowing where your car and your kids are, although some teens may consider it just another form of helicopter parenting.