A HK product that came out a few years ago with the intent of use in the majority of BMW's lineup as a navigation system. It combines a head unit and audible/text nav directions into a 1 DIN box.
http://www.uucmotorwerks.com/98M3/images/TP1.jpg
They're still available, new, for $4 or $500, but probably won't be for long.
US nav data is available.
best, whit
EDIT: other euro car manufacturers used this system, as well (Audi, VW(?)).