Like Facebook, using a so-called "telematics" service like OnStar involves certain obvious privacy trade-offs. It's up to you, as a subscriber, to decide whether those trade-offs are worth it. With OnStar, for instance, it can find out where your car is. But in a medical emergency, or if your car is stolen, you want someone to know where it is.

OnStar, the best known service, is linked to a GPS navigation system in your car even if your car isn't equipped with a computer navigation screen. The car shares data with the operators and computers that provide all those nifty services.

But your exact location is usually only shared when you request some sort of service, like navigation or the name of an Italian restaurant nearby.

Every new service OnStar introduces involves some serious discussion about those privacy trade-offs, OnStar execs say. For instance, one new service is teen driver tracking. In this case, the cars can be tracked only using a secure password-protected Web site, OnStar spokeswoman Cheryl McCarron said.

In terms of data, such as vehicle locations, "anonymized" data is kept indefinitely while more specific data is kept only as long as needed to fulfill specific requests, she said.

By Peter Valdes-Dapena @PeterDrives - Last updated January 18 2012: 2:12 PM ET
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