This dash-mounted Nexus 7 (and its brilliant Knight Rider-themed launcher) is a DIY labour of love. It's a great way to get directions, as well as take music and your favourite apps with you.
Ross Mclardy, over at Land of Technology walks through his project step-by-step at the link below, and you can see the results in the video above. Obviously it's not a project for everyone, but the whole project actually cost him less than an aftermarket full-dash system. He took the Nexus 7 apart and connected it to his head unit so that the audio worked, and then he connected it to power so it would stay charged.
The other awesome part of this build is the Knight Rider launcher Ross built. The whole thing was done with Nova Launcher Prime, Ultimate Custom Widget and Tasker. The buttons correspond to apps and features he uses frequently. Ross actually has an entire post just on how to build the UI if you want to try it on your own Android phone or tablet.
We should note that a shiny in-dash unit like this could be distracting while driving. Let your passenger interact with the screen, or pull over if you want to use it yourself. Also, we don't necessarily suggest buying a Nexus 7 just to mount it in your car's dashboard, and the parts required vary across vehicle models. Your mileage may vary: What was an easy fit for Ross may be more difficult for your car, so plan before you jump in.