If you want to use ios just get an Ipad mini and mount it, if you want something cheaper go with a NEXUS7 and stick either of them in the cubby hole.There are a few different people on here doing different things with tablets. Think one of the member traders is selling an IPAD mount.
Can't think of a reason to have a dedicated in car PC these days, just get a tablet.
I went for a more tablet 'ghetto' mount, you can see it in my build thread, link in my profile.