The first tentative tests undertaken by Piaggio for the speed record on the launched kilometer were made with a vehicle weighing 54 kg, consisting of a frame and a duralumin fairing equipped with a 5.4 hp engine. The small bolide, still equipped with a cylinder with deflector piston, was tested by Dino Mazzoncini on August 20 on the Firenze-Mare motorway and recorded a top speed of 112 km/h: a result still insufficient to come out into the open with an official test . The Experimental Department undertook the following year with a machine still with a duralumin bodywork but completely closed. The machine reached 120 km/h, a speed still not very encouraging, which combined with the precarious stability, due to a too high center of gravity, led to the provisioning of the prototype. With the new year Corradino d’Ascanio took over the project and it was thus that in August the Experimental Department simultaneously started the construction of two different prototypes, with the aim of testing the most suitable at high speed. One machine was characterized by a guide with legs extended forward, while the other supported on the knees. They were built "tailor-made" for the sprinters of the plant: the first, destined for Giuseppe Cau, included an MM engine, brother of those already employed in Monthléry (but with longer ratios), while the second, reserved for Dino Mazzoncini ( it is the specimen exhibited at the Piaggio Museum), it was equipped with a revolutionary opposed piston engine (PC), which although not representing an absolute novelty in the world panorama was developed by Piaggio up to the astonishing power of 18 hp. In the P.C. engine the two pistons operated in the same cylinder and for the same displacement the combustion took place on a halved surface, bringing about considerable advantages on the thermodynamic aspect. The engine, thanks to the special operation of the pistons, also limited the mixing of the flue gases with the fresh ones, to the benefit of the yield. The moving masses, moreover, working in the opposite direction, diminished the imbalance of the forces, further optimizing the exploitation of the power. The two machines still without fairing were tested by the two pilots on 3 and 4 December 1950 on the internal runway at the Pontedera plant and the extreme danger of the first was ascertained, which already at 120 km/h tended to lightly lighten the front end. At the end of the month the two cars were dressed in the fairing and tested again, confirming the need to suspend further tests on the part of Cau, the bishop of a machine against his will that could not be controlled. The tuning then continued on the Mazzoncini machine, which with the sole addition of the full-coverage aerodynamic fairing of the chassis demonstrated in the track test to quietly overcome the previous record of the 125 cc class (161 km/h) achieved in 1949 by Gino Cavanna on Mondial. On 9 February 1951, the fireball was taken on the Roma Ostia motorway. Dino Mazzoncini lowered himself on the car supported in position by the technicians from Pontedera and, having brought up the powerful alcohol-powered engine, at 8:05 he set off to cross the section between the tenth and the eleventh kilometer, covering a thousand meters in 20 "and 24/100. He then reversed the march, recording an average speed between the two directions of 171.102 Km/h, the new World Record in the 125 cc class. The record was obtained on the first attempt.

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