Q: Why is the OnStar service ending?

In August 2017, Groupe PSA bought the Opel and Vauxhall car brands from General Motors.  OnStar Europe Limited was not part of this purchase and continues to be a subsidiary of General Motors.

So, as a result of this change of ownership, OnStar services and Wi-Fi services enabled by the OnStar connection (if available in your country) will cease to be available for Opel/Vauxhall/Cadillac/Chevrolet cars on 31st December 2020.