I have a March MY13 R-Design Lux Nav, so had to spec the DAB radio...again a valid comment from @boru if you haven't had a DAB radio before, how do you know what the standard is?
I live in Kent and have thus far figured out that there are four "channels" for me...Kent, London3, D1 National and BBC National. I do not have any problems with the National channels apart from the odd drop out that occurs in the same place every day.
London3 drops off outside London after about 20 miles or so and here in Kent, North is worse than South! I can't comment on other manufacturers DAB quality, but at the same time as questioning Volvo's, have put it down to the transmitter quality where I am i.e. inconsistent.
The key thing to do in a new area is to trigger the "ensemble learn" function and that will re-tune your radio to what's available.
Hope that helps! Darren