GM announced earlier this week that it will upgrade 4 million vehicles with Gemini , Google's family of generative AI models. The rollout will occur over several months and include GM's four brands -- Chevrolet, GMC, Buick and Cadillac -- with model year 2022 or newer. The vehicles must already have Google  built-in, an Android-based operating system integrated into the vehicle dashboard. A representative for GM did not immediately respond to a request for comment. Google built-in operates much like a phone, giving drivers and passengers access to Google Maps, Google Assistant and the Google Play store. Typically, you cannot add Google built-in after you've bought the car. It has to be preinstalled at the factory. GM says Gemini can plan a driving trip that will use the least amount of gas. GM Over the next several months, GM customers will receive a message on their vehicle's infotainment screen indicating that the vehicle is ready for the upgrade to Gemini from the current Google Assistant.…