Well on the RNS-510 is was certainly hardware as it was a different wiring harness that was needed to route the telephone mic into the RNS for voice control.
I'm not exactly sure what's the crack on the MK7, as it's standard on Nav Pro (as Mark above said), and optional on the standard Nav. Whether the additional optional price in the price list (£185.00) is just a change in the coding, which would seem very steep - even for VW if it was just a bit of VCDS coding. More likely there are some hardware changes to add the "voice" module into the infotainment unit in the glovebox ?
