As an owner of a base 07 G35X (who testdrove that same car with factory NAV and spend hours fighting my friends 06 X35 factory NAV) I have to disagree. While the factory NAV is a very nice one, My Nuvi 680 beats it hands down by the ease of use (no lockout, easier to input addresses, better (IMO) GUI, screen can be moved/tilted, it is removable and can be used in another car/rental or while walking). There is no "wire mess" as they are hidden in my console (where I also store my Nuvi), the mount is on-dash, out of sight when not in use and is completely removable (takes under 30 seconds to remove the mount, hide it and the unit in the console while moving the wire under floormat), I can swap MP3 cds in my CD changer (or use my MP3 playier via dash inputs) instead of dealing with trunk-mounted player and dealing with extra memory cards. The voice command feature, no matter how advanced, cannot work perfectly. Oh yeah - $$$$ saved. To sum up, I could afford the expense of the factory NAV, but with better and better equipped portable aftermarket GPS units with additional features found it difficult to justify.