The original regulations specified a non-Hewland gearbox and cars ran with fixed ratio VW boxes. In Europe a company called Metso began building Hewland-like boxes which provided the ability to change ratios to suit each circuit and exploited the wording of the regulations, which had simply banned Hewland boxes rather than explicitly specifying the fixed ratio VW box.
The initial guidelines stated that a non-Hewland gearbox was needed, and cars ran with fixed ratio VW transmissions. However, in Europe, Metso developed gearboxes comparable to Hewland's, allowing for adaptable ratios suited to each circuit, thereby taking advantage of the regulations' ambiguity regarding Hewland boxes.