When you come to think of it, adding GPS functionality to your in-dash car stereo is one of those basic ideas that manufacturers should have come with ages ago, Sony and TomTom partnering to develop two such units, the XNV-770BT and XNV-660BT.

As a result of this collaboration both of Sony's new systems come preloaded with TomTom maps of U.S. and Canada roads while also adding some features that were limited to their stand-alone GPS navigation systems such as IQ Routes, Advanced Lane Guidance, Quick GPSfix, MapShare and more then six million points of interest including gas stations, restaurants, hotels, hospitals and more.

When it comes down to their specifications, both Sony A/V navigation systems come equipped with touchscreen WVGA displays, the XNV-660BT coming in with a 6.1-inch capacitive touch with several hard keys such as volume and key menu buttons while the 7 inch XNV-770BT drops all these in favor of a fully capacitive touch motorized panel display.

The new XNV-660BT and XNV-770BT models feature multi-channel playback with 5.1 channel support, both units coming in with USB and Bluetooth connectivity in order to easily hookup your digital music player, including Apple's iPod or iPhone.

“TomTom’s expertise in navigation and our long-standing tradition of premium audio and video are strongly represented with these new in-dash systems,” said Mike Kahn, director of Sony’s mobile music business.

“This unique partnership and exciting product offerings represent a huge step forward for Sony in the mobile electronics business.”

All in all, I would say the XNV-770BT and XNV-660BT A/V navigation systems do indeed sound like a great alternative for anyone interested in buying a GPS or a audio video system for in-car entertainment, although the $1,300 and $1,000 price tags are quite hard to swallow.