His grandfather Friedrich Joseph Grümmer moved to Brussels in the 19th century, where he set up a saddlery business that specialized in furnishing high-quality carriages.
In the company named after him, Grümmer initially manufactured bodies based on the Weymann patent, but at the same time worked on independent design features.
At the L'Auto Concours d'Elegance in June 1927, Gaston Grümmer created a surprise by being one of the first coachbuilders to offer upholstery and car interior trim in reptile leather.
The following year, Marcelle Rahna presented an eight-cylinder 35 HP Panhard with a coach body and whose interior, covered in snakeskin leather, could be transformed into a sleeping car: the front seats could be converted into a bed, a liquor bar was installed in the dashboard and a picnic kit placed was placed in a wing box.
Grümmer, who took part in the First World War as a pilot, was influenced by aviation and therefore increasingly sought consistent lightweight construction, aerodynamics and body shapes that were as low as possible.