Audi has dabbled in cellphone-to-car interfaces in the past, but it now looks to be stepping things up in a big way, with its new metroproject concept system sporting its very own, apparently self-designed cellphone / do-it-all device. In addition to doubling as a cellphone, the handset (which boasts both Wi-Fi and 3G UMTS technology) will apparently act as an MP3 player, a vehicle control system, and an input for the car's navigation system. As if that wasn't enough, it can also receive pics of any intruders snapped by the vehicle's camera system, and it'll even let you then keep watch on 'em as they speed away thanks to the built-in tracking system. That's, of course, if it ever actually makes it into a production vehicle -- a possibility that Audi so far seems to be tight-lipped about.