The Citroën TUB (from the French Traction Utilitaire Basse or Traction Utilitaire type B) was a light van derived from the Traction Avant passenger car. The van was produced by Citroën between 1939 and 1941. In May 1941 an upgraded version, the Citroën TUC replaced the TUB, but by the end of that year the last of these vans had probably been produced. The TUB is the first commercial vehicle ever equipped with a lateral sliding door. Origins Pierre Michelin and Pierre-Jules Boulanger were brought in to take charge of Citroën by Michelin following their acquisition of the bankrupt auto-maker in December 1934. During the Summer of 1936 Boulanger received the results of an extensive investigation of customer requirements that he had commissioned. The exercise had been undertaken in preparation for the development of a van of approximately capacity - slightly more than the load that could be accommodated by a simple car-based van. Boulanger accumulated a large dossier of photographs, statistics, sketches and comments. From this he laid down a specification which was simple and demanding. To maximise available load space, the new van must position the driver as far forwards as possible on the chassis. It should be possible to stand up in the vehicle, and the load area should be accessible from the driving seat, without exiting the vehicle. In addition to conventionally positioned doors at the back, the load area of the new van should have a door on the pavement side to facilitate loading and unloading. The decision had already been taken to base the new van on the running gear of the company's recently introduced front-engined front-wheel drive Citroën Traction, making it easier to meet Boulanger's brief because, without an under-floor drive shaft, the floor of the load space could be kept low. The van The Citroën product development department had the first prototype running by the Autumn of 1937, and on 12 May 1939 the van was homologated for sale in the French market. Although low floored vans with the driver set well forwards and sliding side-door on the pavement side would have become relatively mainstream 20 years later, in the 1930s the radical new van was quite unlike anything else available. The van took its 4-cylinder engine, initially of 1628 cc, from the company's Traction 7C. In the car the engine sat comfortably just behind the front wheels, but in the van