AFAIK, it's the equivalent of the 'compact' roof on the Westfalia T4 models. (Nothing is new, just forgotten). Built on the SWB model.
It's a nice solution for singles / couples who want to sleep downstairs, as you lose the upstairs bed, but are able to stand in the van when you just stop for a brew, and benefit from much better thermal and noise insulation.
It's the other extreme to my van, based on the LWB van with a 2m upstairs bed but rather different aerodynamic and aesthetic properties

, oh and a loo and separate kitchen area. There was one in between (the hightop) based on the SWB which had a smurf top like mine, but was conventional layout inside, but retained a 1.9m top bed.
Writing this makes me realise how much choice buyers had in the last century!
Edit: I notice the T5 in the link does retain a roof bed, and the roof does look taller than the T4 Compact, but I think it's a kids only arrangement for sleeping.