As a three-wheeled vehicle having a lightweight (under 7 cwt, 355.6 kg) construction, under UK law it is considered a "tricycle" and can be driven on a full (class A) motorcycle licence.

This version featured a new OHV Reliant engine (based on a reverse-engineered all-alloy version of the 803cc Standard SC engine used in the discontinued Standard Eight[7][8]), a new steel chassis and bonded shell design for the body, fully updated visual styling, and was badged based on their number of wheels/bhp.

[9] Unlike Panhard, who responded to the increased cost of aluminium by substituting heavier steel panels, Reliant's choice of the glass fibre technology ensured that the Regal was able to retain its advantageous light weight, with the resulting ability to use smaller, lower powered and therefore cheaper and more economical engines.

Unlike previous Regals, this no longer had a wooden frame and instead had a unitary construction body of reinforced fibreglass.

[10] A few months later, in August 1968, the 701 cc engine introduced in the Reliant Rebel the previous autumn found its way into the Regal.

[11] An example of a Supervan III is the iconic yellow van belonging to Del Boy and Rodney Trotter in the long-running BBC sitcom Only Fools and Horses.

[12] A Reliant Regal is shown in the closing ceremony of the 2012 London Olympics with it falling apart and Batman and Robin coming out of it, a plot that appeared in an episode of Only Fools and Horses.