"Spatial Audio" is Dolby Atmos with Apple marketing applied. When played over a system such as AirPods or HomePods, Apple is using computational sound to try to simulate the effect of surround and height. Other manufacturers like Dolby and Sonos do the same thing. When you play a "Spatial Audio" song over a true Atmos system with appropriate speakers, you get the real Atmos experience. That's why it's not likely Apple can do this on generic car speakers that they can't control. Mercedes already supports Atmos in their Burmester systems, so it's easy for Apple to plug in to.Aint that dolby atmos you're referring to? It can be decoded to up to 34 channels, each of them will emit their own sound track - whereas spatial audio is a psychoacoustic snake oil, that's supposed to enhance 2.0 stereo on AirPods Max/Pro.