Users can lock, unlock, and start their car from an Android-powered phone with a digital car key. The vehicle manufacturer must work with Google to integrate keys in Wallet. Pairing can be initiated from the vehicle app, an emailed link, or the car's head unit in some cases.
Users who meet the device and car requirements on the Get started with digital car key support page can create Digital Car Keys in Google Wallet.
Google works with the Car Connectivity Consortium (CCC) to develop solutions with vehicle and device manufacturers. The white papers released by the CCC on their website give an overview of how the solutions work.
Developers for device and car manufacturers can contact the CCC to ask about how to start.