Sinclair C5 with Sinclair claiming that he had found "very big" levels of interest. Hoover were sufficiently persuaded to allow Sinclair to divert 10 of their employees to modify C5s for overseas export. The bid to sell the C5 abroad failed; the Dutch National Transport Service told Sinclair that the C5 was not suitable for Dutch roads without improvements to its braking system, the addition of more reflectors, and the inclusion of the High-Vis Mast as part of the basic package. Most of the other ten countries that Sinclair inquired of demanded similar changes. The C5's reputation received a further battering when
Sinclair C5 expensively) on the aerodynamics rather than the cycle technology around which the C1 was based. The weight of the vehicle increased to over , far more than Sinclair's desired specification. By March 1983, Sinclair and Wood Rogers had decided to stop the C1 programme. Wood Rogers comments that Ogle were convinced that the C1 would be a flop, telling Sinclair that it would not be fast enough, that its drivers would get wet when it rained and that the battery was not good enough. To meet the steadily escalating development costs of the vehicle, Sinclair decided to raise capital by