With a car PC you have access to cutting-edge navigation features, and you aren't locked into using the expensive and limited system that came with your car.
In-car navigation used to be a status symbol of the elite, reserved only for those who could afford a Lexus or an Infiniti. Now, however, anyone with an in-car computer (or handy laptop) and a GPS unit can have a navigation system. This hack will describe some of the PC navigation software that can give you a near-MapQuest-like experience with your car PC.
Before we start, let's make one thing entirely clear: you will never get aftermarket integration as tight as you would with a factory-installed navigation unit (at least, not without spending a lot of money). Factory-installed units offer such niceties as spoken directions and automatic lowering of the radio volume so you can hear those directions. They also generally present a cleaner interface (steering-wheel controls rock) and better integration with your dash (have you ever tried to shoehorn a 7" screen into a Honda Civic?). But navigation still isn't a common factory option on vehicles below $20,000, so if your budget doesn't stretch to a more expensive car, chances are you'll have to either go aftermarket or roll your own with a car PC.
Once you've decided to add in-car navigation, there are several routes you can take (no pun intended). You can combine a Palm or PocketPC with a CompactFlash-based GPS unit and some software ...