Vespa prototype was completed in September 1945 and began production in April 1946. only 50 units of this Vespa were produced.

The Vespa prototype was completed in September 1945 and began production in April 1946. Initially, only 50 units of this Vespa were produced.

In 1945, Enrico Piaggio, despite having given orders for the construction of one hundred MP5 "Paperino", not yet completely convinced of the Spolti project, solicited the intervention of Corradino d'Ascanio. The brilliant technician, who had marginally contributed to the design of the "Donald Duck" (in the study of an automatic gearbox envisaged in principle) was, however, not inclined to fill a subordinate role and requested the possibility of putting his hand to a completely new project. D'Ascanio, who had not moved to Biella following the war events, began to sketch the first sketches of the project in a small settlement in Fornacette, near Pontedera, where in 1945 the Technical Project Office had temporarily moved. In the new study, signed MP6.

He first decided to do away with the central tunnel, introducing the in-line gearbox, a solution which made it possible to eliminate the chain, making the engine a single unit with the rear wheel. Instead of the fork traditionally used in motorcycles, he adopted a cantilevered monotube capable of allowing the tire to be quickly removed in the event of a puncture: a solution clearly derived from the aeronautics industry, widely used in aircraft landing gear. To make driving easier, he introduced the gearbox on the handlebar, a device that would have allowed the driver to disengage the clutch and change gear with just one hand, an intuition that Piaggio would have taken steps to file as a patent on 23 July 1946. Prepared for the first sketches, d' Ascanio went to the "Poma" barracks in Biella, where the decentralized Technical Project Office resided, to interface with the designers and technicians who would develop the project in detail. In the Vigliano Biellese workshop, in September, the prototype was subjected to the first road tests on the climb that leads from Biella to Oropa. Unlike the "Donald Duck", which relied on a forced circulation system for engine cooling by means of a fan fixed to the flywheel, the first experimental MP6 model relied only on dynamic cooling. In fact, the technicians thought that, thanks to the lateral position of the engine, it was sufficient to open the slits on the bonnet. Cooling actually proved to be almost non-existent due to the large shield which prevented air from lapping the engine of the running vehicle. After several modifications, it was decided to introduce a disc with fins on the flywheel capable of producing a current of air, to the considerable benefit of the functioning of the engine. 

In January 1946, with the return of the workers from Piedmont, five other experimental units were built at the Pontedera plant, slightly different from each other and ever closer to the version later placed on the market.

New model of MP6 read article The vespa 946