Google changed their policy. Porsche consider their vehicle telemetry to be Trade Secret. Porsche also considered that the demographic of customers that deliberately chose Android instead of IOS and wanted to use an in-car interface were not worth the effort.

They have also rolled out CarPlay to most historical vehicles.

Mercedes-Benz original foray into CarPlay was restricted to certain In-Car Entertainment systems, that were only fitted to certain models. They also had issues with Android Auto licensing early on. Early variants could be configured for Android Auto or CarPlay, but not both. This was fixed in a software update about the same time that Porsche resolved their issues with Google.