An android tablet ia a logical choice for a car PC. The device offers additional features beyond regular car stereos. While many car stereos have GPS, the android device offers a more intelligent GPS. It has all of your google contacts addresses already in the GPS, it has your calendar with events and their locations, Chrome to phone can automatically send directions from your computer to your car. The device can store music, use internet radio, or play music using a cloud player such as Amazon cloud. These are features not available on even the most high end luxury cars.
I recommend choosing a tablet that already has a car dock....