[Android Auto General] mikereidis:
- Yes, Pioneer or the other company I forget. I don't expect much support from Pioneer, but their products are supported by other companies, and there's a good critical mass of users to allow Google searches for issues. Firmware v1.03 seems good and may never be updated. Next years HUs will have new features (Wifi ?) which won't (or can't) be ported to this years HUs.

- Yes. HD and Sirius are pretty US specific.

- Yes. At least somewhat. Worlds better than watching videos at least.

- Note that custom ROM project for some Pioneer HUs is just started. No guarantees of course. In theory the stock HU firmware can forever stay at v1.03 and new versions of AA on the phone will breathe new life into it, as/if Google updates features. I think Google will have to support "old" 2016 HUs for a "good number" of years, or people driving 2016 cars with 2016 HU firmware will be hopping mad before their leases or loans are finished.

- Stock Android 5.0+ devices that pass Google's Compatibility Test Suites should generally work, but there have been some "beta" type issues on some popular Samsung devices at least.

- MANY popular apps are not supported by AA. Or rather some app categories aren't supported by AA and many popular audio and messaging app developers have not added specific support for AA. Some developers have felt "burned" by making special Wearable or TV apps and finding there's little demand for those features. Also, advertising is not allowed in AA compatible apps and most Android users do not pay for apps.

- Yes, there is a layer there much bigger than mere mirroring of video and touch. It's Google's framework and APIs specifically tuned and restricted for automotive infotainment functions. HU may or may not run Android, but it's easier and faster to run it on Android: example: Keycodes match and video decoder and encoder are symmetric. Pioneer runs Android underneath and that helped them put out AA HUs faster than the other guys.

- Android Auto APK is about 30 megabytes. Apps that support AA are the same size whether you use AA or not.

- $500 something for Pioneer 4100NEX.

- Yes, runs standalone.

- Yes, any app runs, but landscape mode for apps is important. And there are "Car Mode" like apps such as Automate that try to provide something similar to AA.

- I guess.

- Root, sure.

- Torque, of course.

- $300 or so ? Some made for specific cars can be much more.

- Yes, no support. More tolerable if source code is available.

- Many "gotchas" I guess. Pioneer comes with external mic and it works well for me.

- Yes, I expect average lifespan of CHUs to be lower than "Western World" major brandname HUs. Who knows though, and maybe we'll want to upgrade our HUs every few years anyway, regardless of quality.

Android Head Unit would be a wonderful option IMO if an "automotive grade quality" HU was available for a decent price. Make it last at least 2-3 years, running new Android versions within 6 months of Nexus devices, be able to run common tasks quickly, and price it from $500-$1000. AFAICT no such device exists, or has even been announced at any price (Parrot is old vaporware).

So if you need real Android in the car, your options are: mounted phone or tablet or CHU, with all their pros and cons. Or maybe the Appradio Unchained Reloaded app and a Pioneer HU.

If AA and "classic stereo" functionality are all you need, Pioneer AA HUs' start around $550 USD or so.

If you "got no money" you mount your existing phone or tablet. If you want AA you can run my Headunit app, or you can get something similar with apps like Automate.