OnStar Corporation is a subsidiary of General Motors that provides subscription-based communications, in-vehicle security, hands free calling, turn-by-turn navigation, and remote diagnostics systems throughout the United States, Canada and China. A similar service is known as ChevyStar in Latin American markets. OnStar President declared in September 2011 that the service had more than six million customers.

A new aftermarket interior rear-view mirror with a built-in OnStar module, branded as OnStar FMV, became available to the public on July 24, 2011. It provides some of the features an OEM system has, such as Automatic Crash Response, Stolen Vehicle Tracking, Turn-by-Turn Navigation, and Roadside Assistance.

The OnStar service relies on CDMA mobile phone voice and data communication, primarily via Verizon Wireless in the United States and Bell Mobility in Canada, as well as location information using GPS technology. Drivers and passengers can use its audio interface to contact OnStar representatives for emergency services, vehicle diagnostics and directions.