Some advice about what to look out for (MK5 GTi)

[Dogbucket]

Out of interest, can you use the stereo, whist in Nav-mode on the MFD2?

yes you can switch away from the map display to the radio and still have the directional arrows and nagging betty telling you where to go. You can adjust her volume relative to the radio/cd/aux

[Teutonic_Tamer]

The MFD2 also allows full auto zooming of the map display even when not using active navigation.  It also allows you to select unlimited POIs (unlike the RNS510), and can also accept an external a/v input, such as a TV tuner, DVD player, or a PhatNoise box.

I also thought the later MFD2s (the DVD based ones) allowed the playback of mp3 cds? 

Oh, the MFD2 can also be set to record and store traffic announcments when you are not in the car too - which is very cool, especially as the pre-2007 DVDs didn't have TMC in the UK.

Basically, the MFD2 and the RCD500 are both a quantum leap over the standard RCD300