Three-wheeled cars are a curious species ... as a legal workaround (like in the case of the Reliant Robin, which could be driven with a motorcycle license) or simply as a design exercise.

when the only three-wheeled saloon that Reliant had on sale was the ancient Regal Mk7 (with its ’60s-style miniature tail fins). Then along came the ultra-modern looking (by three-wheeler standards) ...