I know it's an old thread, but in case anyone is now trying to do this. I'm also using emteria for car play, and got the setup working just fine, fast, Bluetooth, all good. Just need to find a good speaker/mic for it.
Also, I'm not sure how to better do the power thing the best way possible. Maybe a powerbank as Marty suggested, but since I don't use the car every day, that might not work out well.
Here's my setup:
- Raspberry PI 3 Model B
- Rapsberyy PI official 7 inch touchscreen
- Carlink Kit Dongle - Model CPC200-Autokit PRO (has wireless support): using the AutoKit apk
- Class 10 64gb micro SD Card
Besides the car play working fine, I also installed a snes emulator there so my kid can play on longer trips.
I'll post back when I figure out the best way for power, but right now it's not that bad. It takes around 30-35 seconds to boot up.