The foul weather protection was an afterthought
Several months after the C5 was launched, and it was obvious to the press that things were not good with Sinclair Vehicles, one of the stories doing the rounds was that Sinclair had reacted to criticism that the C5 was useless in wet weather by "rushing out" the foul weather accessories - the side panels, and weather cheater.
What Rubbish!
The full range of bad weather gear was featured in the C5 launch brochure, and was also shown in the C5 Accessories catalogue which was distributed with all C5s. See the Accessory Catalogue here.