Among BMW’s most fascinating and rarified post-war production models are those with coachbuilt bodies provided on a sub-contracted basis, like the E9 3.0 CSL done by Karmann, Baur’s E10 Cabriolet, and even the 3200 CS from Bertone.

But none of these stellar limited-production BMW’s rival the mystique and rarity of Maggiora’s 1600 GT from 1968.

With its wonderfully proportioned fastback coupe bodywork styled by none other than Pietro Frua, this bizarre but beautiful model was in production for fewer than 14 months, during which only 1,259 examples escaped Maggiora’s factory in Chivasso, outside Turin.

Prior to BMW’s purchase of Hans Glas’ eponymous vehicle manufacturer in 1966, Maggiora was churning out bodies of this grand touring design as the Glas 1300.

After BMW’s purchase, Frua’s design was lightly updated with the marque’s signature kidney grille, badges, and compound taillights in addition to new 12-volt electrics, an independent rear suspension, as well as a four-speed trans...