In theory, Android Auto is a lot like Android Wear in the sense that the dash screen and interface is really an interface optimized for the dashboard for interacting with the phone. It's got a few, simple, widely spaced buttons and a voice interface designed to enable you to play music and send messages without getting distracted and crashing the car.
As with Android TV, it's this smartphone centrism that makes the offering compelling. It's also interesting to note that Apple's in-dash system, which is called Apple CarPlay, also puts the smartphone in control and that's what compelling about that product, as well.
The smartphone controls your fitness sensors. Google announced its Google Fit for Android program, which is a set of APIs for app developers that enable third-party fitness monitors to all talk to apps on your smartphone.
In the past, most fitness-sensor applications—including those running as apps on smartphones—ran in the cloud. This has been changing for some time, with smartphones becoming more central. But with Google Fit, that smartphone centrism is locked in.
The smartphone even conquers your Chromebook. Google demonstrated the Chrome OS' future capability to run some Android apps.
What that means from a developer perspective is that Android development will get you not only on the world's most widely used operating system ever, but also on Google's Chromebooks, which is slowly gaining traction in schools, enterprises and elsewhere.
Google demonstrated the Android versions of Evernote, Flipboard and Vine running on a Chromebook.
The phone also acts as an authentication device for Chromebooks. If the laptop detects your authorized Android phone within range, you don't have to enter your username and password. It authenticates you automatically.
And like Android Wear smartwatches, Chromebooks will soon display Android smartphone notifications, including notifications about the state of your phone's battery.
What Does It All Mean?
So now we have two conflicting models for the post-PC world. Ironically, the Apple model is somewhat cloud-centric with all devices, except for Apple's CarPlay and upcoming iWatch, essentially equal and synchronizing through iCloud.
And then we have the Google version, which is the smartphone in control of everything.
Over time, I believe Apple's model will come to resemble Google's and that future Apple TVs, future home automation applications, and even future desktop and laptop computers will become increasingly controllable by and subservient to the phone in your pocket.
Welcome to the post-PC world. It's the smartphone's world now.