And often it's simply about building and registering more cars – occasionally it's about allowing designers or engineers off the leash to come up with something truly special.
Whatever the reasons behind the thousands of special edition cars produced over the years (and that's just the Mazda MX-5 and Fiat 500 combined), we've picked 25 limited-run cars that show the highs and lows of the special edition. We'll leave you to work out where on the spectrum each car sits... We'll also tell you, where possible, how many survive on our roads today.
Fiat Panda Italia 90 (1990)
When Italy hosted the World Cup in 1990, Fiat got in on the action with this limited-run Panda, complete with hub caps that looked like footballs. You do at least get exclusivity; just three remain on UK roads, it seems.
Mazda MX-5 Le Mans (1991)
Mazda has launched a large number of special edition MX-5s and few of them are worth more than a regular model. But one of the few that's become collectible is the Le Mans, built to celebrate the Mazda 787B's win in the 24 Hours and recipient of one of the lairiest factory paint jobs ever. Just 24 examples were made, each with a turbocharged 1.6-litre engine rated at 150bhp instead of the regular 115bhp. 11 examples survive on UK roads today. VERDICT: Good
Renault Clio Williams (1993)
The Clio Williams proved such a hit for Renault that it ended up producing a second take on the formula - and then a third, which didn't amuse buyers of the first run very much. Created as a homologation special for Renault to gain entry into the French Rally Championship, the Clio Williams packed a 150bhp 2.0-litre four-pot and was such a blast that Renault had no trouble shifting 5400 of them, before then knocking out another 6700 of the second and third editions; 136 survive on UK roads, and half-decent ones cost from £15,000. VERDICT: (Very) Good
Volkswagen Polo Harlequin (1995)
The Polo Harlequin was such a success that in the US, Volkswagen introduced a Golf Harlequin in 1996, which wasn't sold in Europe. With each car featuring an array of colours from its palette, Volkswagen hoped to sell up to 1000 Polo Harlequins - but production ended up running to 3800. Now they're very sought after with plenty of replicas having been created. 25 are left in the UK, and one is for sale right now for £3195. VERDICT: Good
Rover 200 BRM (1998)
When the Rover 200 BRM was unveiled in 1998 there were many who sneered, but there's now a madly enthusiastic owners' club that caters for these neatly styled hot hatches based on the contemporary 200 Vi with its 143bhp K-Series engine. The red carpet and quilted leather seats were a bit OTT, but the alloy details and British racing Green paint looked neat. The jury is still out on the orange nose though, redolent of 1960s BRM racers. 87 are left, but the market likes them and used ones cost upwards of £7500. VERDICT: (Not) Bad
Mitsubishi Evo VI Tommi Mäkinen (2000)
Sometimes all the stars align and a special edition comes good - really good. Of the many and varied Evos built, the Evo VI-based Tommi Mäkinen Edition is the most sought after with its white Enkei alloys, Recaro seats with ‘T. Mäkinen Edition’ stitched into them and a remodelled front bumper. Created for its home market, Mitsubishi didn't bring any Tommi Mäkinens to Europe - but plenty have found their way here in the meantime. VERDICT: (Very) Good
Rover 25 Art Car (2002)
An array of people got paid to be a part of this ridiculous project, not least of all British fashion designer Matthew Williamson. From the too-much-is-not-enough school of design, the Rover 25 Art Car featured lashings of pink and gold both outside and in. The exterior was relatively restrained compared...
Rover 25 Art Car (2002)
... to the interior. A production run of 50 more subtle examples was set to be built and MGR even produced a brochure, but they were never made - the original show car survives though. VERDICT: Bad
BMW M3 CSL (2003)
A BMW M3 is never a bad start point for any special, but when you do all the right things, such as lighten it by 110kg and increase the power to 360bhp, add quicker steering and beef up the brakes, the result is going to be immense. UK sales totalled 422, from 1400 CSLs built; 157 examples remain on UK roads today; you'll pay at least £45,000 for something decent.
VERDICT: (Very) Good
Subaru Impreza RB320 (2007)
Subaru hasn't been shy in producing limited-run Imprezas over the years, so we were spoiled for choice when it came to picking one. We could have opted for the RB5, the P1 or the 22B but instead we've opted for the later RB320. Arguably the quickest point-to-point Impreza of the lot, the RB320 was built in honour of rally king Richard Burns who died in 2005.
The RB320 came with a 316bhp Prodrive-fettled engine, black paint, 18-inch alloys and completely overhauled suspension; now these cars are highly prized. 168 remain on the UK's roads, down from 248 in 2011. They come up for sale occasionally around the £30,000 mark. VERDICT: (Very) Good
Renault Megane R26.R (2008)
Renault has produced an array of hot Meganes over the years, many of which have been quite brilliant. But none more so than the 230bhp R26.R, which was 123kg lighter than a regular Megane R26 and came with recalibrated suspension plus an (optional) roll cage. Renault struggled to shift them when new; now hot hatch fans can't get enough. 37 are left, and they cost from £20,000 on the used market. VERDICT: (Very) Good
Citroen C3 Pluriel Charlston (2008)
For a certain age of classic car fan, the most memorable Citroen 2CV is the Charlston edition of the 1980s, which Citroen decided to ape with this update on the theme, to celebrate 60 years of the 2CV. Using the same colour scheme as the original, the only thing appealing about the Pluriel Charlston was the black and burgundy paintwork. After that it was just as dire as the regular car. 31 survive today. VERDICT: (Very) Bad
Fiat 500 Ferrari (2009)
The list of special edition Abarth and Fiat 500s seems endless, but perhaps the most appealing is this one, created in conjunction with Ferrari technicians and based on the Abarth 695, in the days when Fiat owned Ferrari. The 1.4T engine was boosted to "more than 177bhp", the suspension and brakes were uprated while the interior and exterior were sexed up. Just 152 came to the UK. VERDICT: Good
Honda Civic Type R Mugen (2010)
It may have come with a near-£40,000 price tag, but with just 200 examples of the Civic Type R Mugen available, Honda dealers didn't have to try too hard to shift these ballistic hot hatches. Peak power was boosted from 208bhp to 237bhp, a limited-slip diff was fitted while the brakes and suspension were completely overhauled. Built for UK buyers only, the Mugen was a landmark hot hatch that was bonkers - and all the better for it. 146 examples of the original 200 survive. VERDICT: (Very) Good
Bugatti Veyron L'Or Blanc (2011)
Considering the Bugatti Veyron was hardly a mass-production car - it took a decade to make 450 of them - it seems mad that a multitude of special editions were built. However, these were hardly mats & flaps specials with a go-faster stripe; many were one-offs created to garner publicity. These included the Hermes, Venet, Bleu Centenaire and this - the L'Or Blanc which featured porcelain dotted about its bodywork and cabin. VERDICT: Good
Smart ForTwo ED by Jeremy Scott (2012)
Smart has come up with quite a few specials over the years, in a bid to boost sales of its ForTwo. Most of them have been pretty innocuous - a pretty colour scheme here and a set of decals there - but this one, penned by fashion designer Jeremy Scott, was bonkers. Based on the Smart ForTwo Electric Drive, the smart forjeremy made its debut in 2012 with a limited run of petrol or electric cars available from 2013. VERDICT: Good
Range Rover Evoque Special Edition (2012)
Land Rover appointed Victoria Beckham its Creative Design Executive in 2010, and when it launched the Range Rover Evoque the same year there were 200 copies of the Special Edition up for grabs. Each one came with matt gunmetal paint, gloss black wheels, tan leather trim and a fitted luggage set. Initially available only to Chinese buyers, each example cost £79,995 and US$129,000; just 200 examples were built. VERDICT: Not Bad
MG6 BTCC Edition (2012)
Celebrating coming third, behind Honda with a 1-2 for the season, MG unleashed this beast, which was such an animal that it had to be electronically limited to 120mph. Liberally treated to decals and stripes galore, the BTCC Edition also featured such luxuries as 18-inch alloys, black gloss exterior detailing and a matt black roof.
Your £17k also secured tickets to a round of the 2013 BTCC championship, plus a team jacket and hat. There must have been riots in the streets... Four are left. VERDICT: Bad
Infiniti FX Vettel Edition (2012)
Nissan's luxury sub-brand was struggling to gain traction in Europe, so what better way to grab a few sales than to introduce a £100,000 variant of the FX? A tie-in with F1 racer Sebastian Vettel, it was almost twice the price of a regular 5.0-litre V8 FX by the way and in return for the £40,000 premium buyers got an extra 30bhp, some fresh wheels, a spoiler or two and an overhauled interior. All five models ever sold in the UK survive to this day. VERDICT: Not Bad
Range Rover Holland & Holland (2014)
The first Range Rover Holland & Holland arrived in 2000, based on the P38; 400 were made. The third-generation (L322) Range Rover also came in H&H guise and now you can buy a fourth-generation Rangie in H&H form. Prices started at £180,000 with all cars being based on the Range Rover Autobiography Black.
Luxury abounds with tan leather trim, metallic green paint, lashings of walnut and a pair of Holland & Holland guns in the boot, in their own aluminium cabinet. VERDICT: Good
Jeep Renegade Dawn of Justice (2016)
This is where special editions go wrong. Launch one with 500 examples available, and by the time they're ready for their first MoT the film is long forgotten. Named after the Batman v Superman: Dawn of Justice film, the Renegade came with decals and posh 18-inch wheels, so it's not really a landmark motor. 494 examples are on UK roads. VERDICT: Bad
Bentley Continental GTC by Sir Peter Blake (2016)
Created by British Pop Art legend Sir Peter Blake (who designed the cover for the Beatles' legendary album Sergeant Pepper), each of this Continental GTC's four seats was a different colour while the bonnet featured lurid colours - although the lower portion of the car was British Racing Green as "a nod to Bentley’s motorsport heritage".
The car was built to raise funds for the charity Care2Save and when the Bentley was auctioned in summer 2016 someone paid £250,000 to secure it. VERDICT: Good
Ssangyong Korando DMZ (2016)
We'd like to say that you'd have to be a hell of an exhibitionist to drive one of these from Korean firm Ssangyong, but if that paint job is doing its job nobody would notice you. Initially created as a one-off, Ssangyong dealers started clamouring for copies of the DMZ to sell; all that separated this military-inspired pick-up from the regular Korando was the paint job. VERDICT: Bad
Nissan Gold Leaf (2016)
Keen to garner some publicity for its all-electric Leaf, Nissan decided to give any TeamGB and ParalympicsGB squad members a free gold-wrapped Leaf in return for securing a gold medal in the 2016 Brazil Olympic Games. Things kicked off with Max Whitlock and George Nash receiving Gold Leafs (geddit?) with Paralympians Richard Whitehead and Matt Wylie also getting one. VERDICT: Not bad
BMW M5 Competition Edition (2016)
With an all-new M5 about to be unleashed, BMW gave the outgoing F10 model a suitable send off with the 600bhp Competition Edition. Not to be confused with the Competition Package launched in 2013 (with 575bhp), the run-out special was limited to 200 units globally at a hefty £101,000 apiece. Buyers could choose from black paint or white. 16 remain in the UK today.
It was never sold in America - they got the US-market only 600bhp M5 Pure Metal Silver Limited Edition instead, of which 50 were produced. VERDICT: Good