I am also a android fan (apple hater), so my opinion is a bit biased.
I tried to do a android dash in my car not too long ago, i ran into a few issues:
1. I wasn't able to find any really friendly apps at the time that would make car use friendly and intuitive. Im sure this has been fixed by now.
2. So far as I am aware, there is still no way to connect the tablet to steering-wheel controls to change volume, track, etc.
3. I wasnt able to have the tablet turn on when the car was started, or turn off when ignition was turned off. This meant I had to power it up and down each time. Powering up after a few days of non-use led to 10-15 minutes of battery charging before it could start playing music.
I still want to do it eventually, but #2 and #3 havent really been solved yet, so ill keep waiting.