The theme of this year's Google developer conference was putting Android everywhere, so it ought to be in the thing that takes people everywhere: the car. Android Auto works by plugging in an Android phone running the L operating system. The phone displays an "A" on the screen and you can no longer operate it. Instead, the phone sends up its information to your car's display. Google calls it "casting," but the key thing to know is that very little of the smarts of Android Auto live in the car's computer — the whole thing is run off of your phone.
We sat down in a Hyundai on the floor of the Moscone Center in San Francisco and started hitting buttons. Unlike your average car audio system, Android Auto was responsive and quick. We were able to jump between the five main tabs without waiting around for the screen to refresh — it's nowhere near the speed you're used to on your phone, but it's worlds better than what car manufacturers usually saddle you with. Google says the nice thing about Android Auto is that it's tied to the upgrade cycle of your phone, not of your car, so you're more likely to get a faster, better experience in your car than you otherwise would. Most people upgrade their phone every couple of years, but their car stereo basically never. Android Auto would change that.
Android Auto has sections for navigation, phone, music, and car status, with a fifth section for the main overview screen. That main overview is essentially Google Now on your car, including contextual notifications and shortcuts to, say, playing music. Since it's basically Google Now, you can do the same basic stuff here, including voice search and voice commands.
The other nice thing about having your phone power your car interface directly is that the apps you already have on your phone can work in your car. Double-tapping on the music icon, for example, gives you a list of car-compatible apps that you have installed on your phone.
There's actually not a ton more to say about how Android Auto works based on what Google has shown today. And to be honest, that's a good thing. Google has a habit of over-engineering problems to the point where the solutions feel too complex. But Android Auto is straight forward: you plug in your phone and your car's screen becomes an alternate version of your phone's home screen. An interface that doesn't get too clever is exactly what you want in the car.
Unfortunately, we won't know exactly how many cars will actually support Android Auto for quite some time. Google says we'll see cars that work with it before the year is out, but beyond that we just have to trust that the many partners that have been announced will come through. Who knows, maybe we'll see cars that support both Apple and Google smartphones — at which point, it seems like most cars wouldn't need a built-in system at all.