Surely "mundane" = common. "special" = rare. In other words the boxter would be special if built in the same numbers as the Morgan. That would make seeing one or riding in one that much more of a event.
I'm not knocking the boxter. Its way more of a car in an engineering sense than a morgan, as indeed are the typical mass produced family saloons. Its also way more common and far less quirky.
I think this is a gross over-simplification - 'Special' is not just to do with rarity, whilst that is an important element (though with Ferrari heading for producing 10,000 cars a year are they still 'special'!) it also incorporates ability, price when new, marque perception, critical acclaim, etc, etc. It is as Adrian says very much a subjective subject, though I also think that quite often special cars have some flaws, and Morgan's certainly score on this criteria!
No one could deny that a Porsche GT3, or GT3 RS are special, as also imho is the Cayman GT4? When the 911 R came out one was immediately sold in the UK for £1 million, someone thought that car was pretty special and they produced 991 of these - circa Morgan's total production in a year...