How Terminal Mode works is actually surprisingly simple, according to Volkswagen and Nokia engineers: it's basically just a VNC terminal that shares your phone's display, and transmits your inputs back to the phone for processing. The downside is that your infotainment system is generally only as good as your handset, relying on its wireless connection, GPS, processor and multimedia support -- though we're told external modules might be in the works -- but the obvious upside is full control over your personal device without fiddling with its tiny screen. Connecting the two is dirt-simple, and will get simpler yet -- we plugged a USB cable into a Nokia N97 and clicked on "IP Passthrough," and in a couple of seconds had a full touchscreen interface, though VW told us it'll sync automatically as soon as you connect in the final implementation. From there we got access to a specially-augmented car mode for the device with widgets for music, web, weather and GPS, as well as apps and the Ovi Store, plus large buttons for making calls and sending text messages with a vehicle-optimized touchscreen keyboard. Like Nokia originally told us, some of this functionality (and third-party apps deemed danger) will be disabled while the vehicle is moving, and we got an update on how that might work; in addition to relegating apps to various categories that the car can disable, the system may be able to detect when the phone is accessing certain functions -- say, full-motion video -- and automatically shut them off.
The concept's sound and the features robust, but boy, was the interface slow. We've got no (new) bones to pick with the N97, but it was clear the 424MHz handset was holding us back, and at no fault of Terminal Mode itself. Though the Passat's squishy resistive touchscreen had no trouble translating X, Y finger coordinates to the capacitive N97 (VW says capacitive auto head units are on the way, never fear) every reaction to our press caused a painfully long pause, and testing out the commands on the phone's screen instead, the system suffered the same delay, causing us to take a pit stop every time we wanted to change tracks or alter our driving destination. Since the final Terminal Mode specification supports phones of all sorts (not just Nokia or the N97) we're pretty sure a nice 1GHz ARMv7 chip would make us sing a different tune, but it's clear that there's a lot of work to do at the software end of things to make streamlined car interfaces, so we'll have to see if apps can do the trick on rival devices or whether device or OS integration will be needed. For now, enjoy a quick look into the future of connected autos!