***See my updated videos here, I fixed all the issues I point out in the video, and I manage to turn this into a fully functional headunit replacement:
Part 2 - hifi audio and backup camera -
https://www.youtube.com/watch?v=TVv2fjcHfGc&t=2s
 
Part 3 (6 month update part 1) - open auto pro, Backup Camera Script & Shutdown Script -
https://www.youtube.com/watch?v=vMvMXd4RvdA

Part 4 (6 month update part 2) -bt calling, steering wheel controls, wireless AA, kodi -
https://www.youtube.com/watch?v=Z-0post9HVo

Graceful shutdown using a delay-off relay timer -
https://www.youtube.com/watch?v=rknBevexOcU

My goal was to replace my OEM car radio with a 100% DIY Android Auto HU (open auto) running on a raspberry pi.  Considering android auto is meant to supplement an existing head unit, not replace one, this should be interesting.  I managed to make it work.

I show crankshaft in this video, but I am now using open auto pro, which I consider a superior product.  To try it out, go here -
https://bluewavestudio.io/

*** Full Parts List ***
Official Pi 7" touchscreen ($70) -
https://amzn.to/2VEcNKG

Raspberry Pi B+ ($39) Make sure to also get a micrsd card to install the crankshaft OS if you don't have one already-
https://amzn.to/2C2q0Uq

10Amp 12V to 5V Power supply ($15) -
https://amzn.to/2VJ7sBB

Long USB Cable to run from Pi to your phone (This is the one I used... just make sure the one you use is high quality DONT CHEAP OUT ON THIS)($10) -
https://amzn.to/2LPSIfG

USB sound card (use this option if you have a standard amplifier with low level RCA Inputs) ($8) -
https://amzn.to/2LTZalQ

Stereo lapel mic (MAKE SURE ITS STEREO, MONO WONT WORK) ($15) -
https://amzn.to/2Az8irJ

If you want to use digital output (like I am), you'll need the hifi digi+.  ($35) -
https://amzn.to/2RzbdKG

If you use the hifi digi+ (which will offer the highest SQ), then you must use a usb mic instead of a stereo input mic.  You won't need the USB sound card anymore.  Here's a quality and reasonably USB mic that is proven to work combine it w/ a USB extension cable to get additional length out of it ($16) -
https://amzn.to/2R7DlVX

To control volume, you need a line level attenuator.  Here's a cheap one that i've used on other projects and I know works well ($9) -
https://amzn.to/2VzIiFN

To make phone calls, you need an external bt adapter.  Even though the pi has bt built in, it does not support hands-free profile (HFP), so you cannot use it to make phone calls.  Here's the one I am successfully using for both streaming music (A2DP) and phone calls (HFP) -
https://amzn.to/2C0Ml4S

12V relay board ($10) -
https://amzn.to/2Rv6ee6

GPIO breakout board ($21) -
https://amzn.to/2Rwdy9n

Backup Camera ($23) -
https://amzn.to/2LW6RZ6

Camera extension module (to run HDMI to rear of car - be sure to use a high quality 25ft HDMI cable - don't cheap out!) -
https://amzn.to/2Rxjij4

That covers the basics of the parts.  Those parts will give you basic functionality, including voice input for google assistant.  You need an external amplifier however as the pi does not have built-in amplification, and as far as I know crankshaft doesn't support pi-based amplifiers (as of now).  If you don't want to install an external amp in your setup, then you need to use your existing radio and use this as an add-on.  In that case, you would just connect a standard 3.5mm aux cable from the USB sound card to the aux input on your radio for sound.

You're also going to likely need a custom fascia or enclosure to put the screen into, and you'll need some way to tie into your car's accessory wire and ground as input to the power supply.  I used a stereo harness made for my car I bought on crutchfield.

Any questions just ask in the comments!!  A follow-up video is coming soon to expand on what this can do!!