It looks to me that it should be a tentative to improve the look of the basic model. It has a soft top to protect from bad weather and due to that addition has been necessary to open a door in the right side to allow the passenger to go into the car. It could be a work of a known coachbuilder at its time, but I'm unable to find any specific information. The only variety that I've found is the possibility of have the car with two independent motors attached to each rear wheel, but I don't think that this is the case of the puzzle's picture.
