The first prototype to be ready was that of Renault, that also had received orders for six sets. It was tested between 15 and 23 April 1930. Certain defects were found and remedied, after which the prototype was again tested from 3 June. A second prototype, fitted with a rubber track, was tested between 28 April and 12 May. This other track type was shown to be too weak. The project had as factory designation Renault UE, a chronological letter code without further meaning; the smaller trailer was the Renault UK. The Vickers suspension with double track guides was imitated. For Renault this new suspension type, that he patented despite its obvious Vickers ancestry, offered the solution for severe problems he had experienced trying to adapt his existing suspension models, using single track guides, to a high velocity vehicle without increasing the chance that the track would be thrown at higher speeds. Renault hoped to further develop the UE into a light tank by adding a turret; accordingly the hull resembled a tank chassis rather than a dedicated supply vehicle.