Over the years many Silver Cloud series cars have been adapted to convertibles by virtue of the rarity and inherent high value of the original coach-built variants. The vast majority of these have been in the form of 2-Door models where the two front doors have been extended in length and the two rear doors have been removed and often utilised to form the extended rear quarter-panel. This simplifies the adaptation by removing the need for complex front and rear window operation.

The relatively few 4-door adaptations produced vary in design but usually utilise the existing door/window frames and removable ‘B’ post sections; these aspects are not in accordance with the original Mulliner design and results in a vehicle which does not function as a true 4-door convertible whereby the hood can be raised and lowered at the touch of a button without the need to manually remove or adjust component parts. Furthermore, many of the fittings in these vehicles are not true to the original designs but rather modified versions of other more readily available parts.

This is not the case with the PKW. 4-Door which, based upon the shorter wheelbase chassis, is totally unique in that it has fully retractable electrically operated combined rear drop glass/quarter light which describes a 90 degree arch in operation instead of the standard vertical movement, thus accommodating the whole window within the door. This adaptation does not use any of the existing window frames. Furthermore, none of the rear seat space or legroom is sacrificed.

All fitments, i.e. sun visors, hood latches, interior lights etc. are either original or hand crafted copies from the original coach-built cars.