I think this is the French Formule Économique or "Forméco". The cars were developed in the late 1960s by a garage owner called Paul Flament in the Pas-de-Calais département in northern France, initially as a way of recycling accident-damaged Volkswagens.
The floorpan was shortened, and a lightweight two-seater buggy style body fitted, with steel roll cage. I think it was initially seen as an instruction vehicle for young drivers interested in racing, but it was found to perform well on the beaches and sand dunes in the area, and became popular for racing in those conditions. I don't think it took off in a big way, and seems to have disappeared around the time of the oil crisis in the early 1970s.
