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 stipulated a non-Hewland transmission and vehicles utilized fixed ratio VW transmissions. However, in Europe, Metso started manufacturing gearboxes similar to Hewland's, enabling adjustable ratios tailored to each circuit, taking advantage of the regulations' vagueness, which merely banned Hewland boxes without explicitly mandating fixed ratio VW transmissions.