This "big Mercedes" got its sensational body from Castagna. The construction was carried out on one of 19 chassis from the W07 series, which were then supplied from Sindelfingen to various coachbuilders.
The Carrozzeria Carlo Castagna was an Italian coachbuilder from Milan who designed and built bodies for luxury cars under the abbreviated brand name Carrozzeria Castagna in the first half of the 20th century. Castagna was founded in Milan in 1849 and worked with Isotta Fraschini, Duesenberg, Alfa Romeo, Lancia and Mercedes-Benz, among others. The original company was discontinued in 1954.