Ask any petrol head to draw up a shortlist of their all-time favourite cars and it’s likely to include one or more of the famous ‘homologation specials’; machinery like the ‘whale tail’ Sierra Cosworth RS500, the outrageous 1969/70 NASCAR models like the Plymouth Superbird/Dodge Charger, or the exquisite Lancia Stratos with its Ferrari Dino V6. Less widely known creations include the Mitsubishi Pajero Evolution, a Pajero on steroids, which helped underpin a series of class and outright wins in the punishing Dakar Rally.

Two factors combine to fuel the need for homologation specials: motorsport regulations and manufacturer model ranges. When regulators seek to eliminate prototype ‘works’ machines from a category, in order to make taking part more affordable, they often do so by specifying a minimum production volume for a vehicle to be eligible; typically 200, 2500 or 5000.

If a manufacturer already has a mainstream product with the right basic characteristics (such as powertrain type, weight distribution, handling balance) it will just modify the showroom model for competition. If it has no suitable starting point, it may create a ‘homologation special’ which contains all the necessary ingredients to provide a competitive vehicle, once modified as permitted by the regulations; in other words, a competition car thinly disguised as a road car.

Though glamorous and sought-after, homologation specials are often highly compromised as road cars: the huge turbo in a Sierra RS500 provides the headroom for competition tuning but sacrifices the driveability of the smaller turbo in the standard car; often specials use lightweight aluminium or plastic body panels which are more fragile than the steel counterparts of the mainstream models and less durable in daily use.

Times have changed since the 20th century; many road cars now incorporate sophisticated all-wheel-drive systems (some with torque vectoring), turbocharged multi-valve engines and sophisticated multi-link suspension. Meanwhile international race and rally categories have tended to polarise into ‘silhouette’ formulae such as DTM, NASCAR and WRC, or prototypes such as WEC and single seaters. These developments have almost eliminated the homologation special. Almost but not quite.

As recently as 2006, BMW made available 2600 examples of its 320si, to satisfy World Touring Car regulations. With bigger valves, shorter stroke and increased bore size, its engine was fundamentally more suited to racing than the mainstream BMW 2.0l models. Offered at a lower price than the 320i M Sport, they were quickly snapped up but only time will tell if they become as revered and sought-after as the original M models.

Higher up the price scale, the GT3 category for racing cars leads to exotic specials from companies such as Porsche, Audi, AMG-Mercedes, Aston Martin, Bentley and many more. But these are not homologation specials in the accepted sense as they do not result in models that are subsequently sold for road use. However, so popular is the formula, that over 40 different models are currently (2016) homologated. GT3 blurs the definition of a homologation special because, in theory, it requires the car to be based on a mass-produced model, yet includes products from small-volume producers, such as Morgan and McLaren.

The approach taken to GT3 by the manufacturers also varies considerably. AMG-Mercedes swaps the 4.0l turbo V8 of the road-going GT for a naturally aspirated 6.2l and makes wholesale changes to the bodywork, fitting wider carbon/Kevlar panels, to create the GT3 racer. In contrast, Porsche uses subtler revisions to transform its 911 GT3 (intended for mostly highway use) into the GT3 RS (intended mainly for track use); the most noticeable change being the extra louvres and ducts to improve heat management during hard use.

The most high-profile homologation special announced in recent years is the Ford GT, designed to capitalise on Ford’s Le Mans history from the 1960s. With a planned production of one car per day until 2020, this is a genuine ‘road legal racer’ and has already secured a 1-2-3 finish in its class at the 2016 Le Mans 24 hr race.

Whether we ever return to the heyday of homologation specials will depend on the direction taken by future motorsport categories; all it will take is for manufacturers to spot an opportunity and justify the business case. We can, however, be pretty certain that if such cars do emerge, they will be a lot more complex than their 20th century predecessors. As long as they remain fun to drive, we can forgive that; a 1000hp hybrid anyone?