more on how the rules were being "INTERPRETATED" (flaunted!). The FIA Group A regs stated that aerodynamic aids and body panels were not to be "adjustable". In 1989 Allan Moffat turned up at Sandown with the front bumper/spoiler visibly at a different angle to the norm. When challenged by a non sierra team, the scrutineers declared it was just differences in panel fit tolerances that could be expected from a mass produced car! Hence the Sierra teams were given a green light to flaunt the rules. The other teams quickly followed suit. It was found by angling the rear downwards downforce was slightly enhanced. It got so bad that some teams were running the bumper with the rear a good inch down from where it was supposed to be. In 1991 they started to bring the whole bumper forward as well!

Here is a pic showing at top what the bumper is supposed to look like when fitted correctly, middle how it looks "adjusted" downwards and lower "adjusted" forwards