Manufacturers contesting FIA Championships were subject to "homologation" requirements which determined the eligibility of particular cars for particular race group categories.  The homologation process involved setting down in detail the exact configuration of a car with specifics on engine, chassis, dimensions, and so on.  The manufacturer then was required to produce and sell a certain number of cars in this configuration, typically 1,000, in order to qualify that model as the basis for a race version in a particular FIA group.

The cars sold to the public are often referred to as "homologation specials" and one of the most famous and highly sought after is the 1973 Porsche 911 Carrera 2.7 RS.  With its distinctive "Carrera" side script and "duck tail" the RS has become an iconic Porsche.  It was sought after in its day as well:  Porsche had no trouble finding customers for 1,000 cars and ended up making well over that figure, 1,580 in total.

This was my first "collector" Porsche, a lovely car which had spent its entire life in Bologna, Italy.  However I never got to enjoy it, as I ended up selling it to my good friend Mauro Borella in part exchange for the 934.