Reliant started in 1935 by making make three-wheeled vans but added a passenger car to its range in 1952. The Regal 3/25 of 1962 was a monocoque construction, made entirely from glass fibre and its new 600cc engine was the first all-aluminium engine in a British car.

For the average car buyer, the Regal offered advantages in low running costs, good economy and lower vehicle tax, and could be driven on a motorcycle licence. When the Morris Minor van was reaching its last days, the Post Office investigated a number of models as a replacement for its fleet of delivery vans. In 1970, 50 Regal Supervan IIIs were trialled with the Royal Mail, although the model was not selected.