Unicorns: The rarest cars you can buy – but should you?

In the age conformity, everybody wants to be exclusive - maybe one of these can help you achieve just that...

To someone they seemed like such a good idea at the time.

Unicorns

These are the halo models that were always doomed to fail – the derivatives that were signed off in a fit of blind optimism, and which would lead to heartbreak in showrooms around the country.

If you’re a second-hand car dealer, you’ll be praying that none of these are offered as a trade-in, because you just know they’ll be a nightmare to shift. But some might make an interesting choice for you…

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BMW 550i Touring

BMW 550i Touring

The 402bhp V8 550i may lack the glamour and power of the M5, but those model-unique twin-exhausts give the game away of this ultimate wolf-in-sheep’s clothing. Most came fully loaded, but ensure yours has the useful head-up display and adaptive cruise options.

There are around 300 on UK roads today across two model generations, but the one you want is the estate of 2010-2017, with just a handful of these ever sold. The fuel and vehicle excise tax bills will be tiresome, but you will be driving one of the most interesting, well-resolved, powerful, and rarest wagons on the road.

We couldn’t find any 2010-2017 models for sale at the time of writing, but there were a few previous gen variants around. For a 2008 550i Touring with 120,000 on the clock you’ll pay £8,000.

Volvo S80 V8

Volvo S80 V8

We salute whoever at Volvo decided to bring this thirsty four-wheel drive 4.4-litre V8 to UK shores. It makes no sense at all, until it does: for those who don’t do many miles, such as retired folk, this is a way to travel in huge comfort and style.

With a near-silent 311bhp petrol engine humming away you might even get 28mpg on a steady run. There are just over 100 of these on UK roads at present.

We found a tidy looking 2008 model with 118,000 miles for just £5,995 – that works out at £19.20 per horsepower…bargain.

Rover 75 V8 Tourer

Rover 75 V8 Tourer

In its final years MG Rover undertook an ambitiously mad scheme to re-engineer the 75 for rear-wheel drive, powered by a Ford Mustang V8. As long as your mileage isn’t great, 22mpg could be survivable, and it would be a gloriously smooth way to transport your family.

Its MG ZT-T 260 twin brother has around 80 examples still on the road; this one? Just 17 in estate form.

Predictably, we couldn’t find any of the coveted 17 for sale at the time of writing. But we did find a couple of saloon examples featuring the same V8 powertrain. The cheapest we found was a tired looking beast from 2004 with 45,000 miles for £9,000.

Volvo V70 T6

Volvo V70 T6

In the market for a comfortable, smooth family wagon without that horrible diesel rattle and future black pump supertaxes? Of course you are, and the 281bhp straight-six T6 fits the bill perfectly. Auto and four-wheel drive are standard, as is a 0-62mph time of 7.2 seconds, going to a top speed of 152mph.

Interestingly, of 190 on the road, it seems a full 27 of those are ‘Authorities’ spec, used by the police and ambulance services. This is a good club to join, and your registration fee will be from around £7,000 for a model with 80,000 miles.

Volkswagen Passat W8

Volkswagen Passat W8

For an apparently staid company, VW certainly does some wacky things: the Phaeton and emissions fiddling spring to mind. But so should this idea of shoehorning a 4.0-litre 275bhp W8 engine into a model that has long been the byword for suburban anonymity.

It even came as an estate, and in both forms only the quad exhausts hint at the bulldozer-knocks-down-garden-wall-of-vicarage-fête potential. From a maximum of 210 or so examples on UK roads, there are now only 80 left; they should be savoured and preserved, and you should volunteer.

We found one up for auction in Scotland with an estimated sale price of £5000.

Jaguar XF SV8

Jaguar XF SV8

If you wanted a top-welly XF from its first generation, the fire-breathing 503hp XFR was the way to go. All of which overshadowed the ‘Super V8’ models, which struggled on with a mere 420bhp.

Insurance costs should be significantly lower than for the XFR into the bargain too – few thieves aspire to stealing such an anonymous car.

A private sell with 95,000 miles and full service history will see you a modest £6,500 poorer.

Audi A3 3.2 V6

Audi A3 3.2 V6

In a world of turbocharged three-cylinder engines, the 3.2-litre A3 sports twice as many combustion chambers, so it’s the perfect antidote to downsizing. It’s also much less frenetic than the S3 alternative; built for cruising rather than tackling twisty roads, effortless mile eating is the V6’s forté.

Unlike many others featured here, the A3 is a genuinely affordable car and there are quite a few of them around, some for as little as £1,800.

Volkswagen Passat R36

Volkswagen Passat R36

The Passat W8 may have proved impossible to sell but that didn’t stop VW from coming up with a sequel – the R36. Despite losing a quarter of its cylinders, power was boosted to 299bhp and as with the W8 there was four-wheel drive to get that power down.

Control freaks were dismayed that there was no manual option; all R36s came with a six-speed automatic transmission instead.

Pull together £10,000 and you can bag yourself a very tidy example with 91,000 and half a years MOT.

Vauxhall Insignia Country Tourer

Vauxhall Insignia Country Tourer

The wealthiest Audi buyers don’t choose an A8 or R8; they buy A6 Allroads. Perhaps this fact wasn’t lost on Vauxhall’s product planners when they dreamed up the high-riding Insignia Country Tourer with its body cladding and four-wheel drive. Launched in 2013 the model was axed two years later.

If you fancy something uber-rare try to find a petrol-powered Country Tourer; there are just six on UK roads. However, none of them are currently for sale.

Citroën BX 19 GTi 4x4

Citroen BX 19 GTi 4x4

Using the same injected 1.9-litre engine as the Peugeot 405 SRi, which was closely related to the 205 GTi’s engine, the Citroën BX 19 GTi came in various forms. Most prosaic was the 8-valve edition (just 13 left on UK roads) while spiciest was the GTi 16-valve (25 left).

Rarest of the lot is the BX GTi 4x4; just four are now in use. If you own one, hang onto it as it’s a future classic if not one already. If you don’t but want one, it will almost certainly be worth more in future.

We found a 1990 16-valve GTi in the classifieds for £7,000.

Ford Galaxy V6 4x4

Ford Galaxy V6 4x4

It would be easy to assume that any Ford Galaxy will have sold in vast numbers and that as a result there’ll be no shortage of survivors of any derivative.

But few buyers opted for the top-spec V6 four-wheel drive models which is why just seven Ghia V6 4x4 autos are now taxed, along with eight even posher Ghia X 4x4 autos. A quietly sumptuous way to get around, and you can be increasingly sure survivors are being well cared for.

But, due to such small numbers left in the UK, none are currently up for sale.

Mercedes-Benz R63 L AMG

Mercedes-Benz R63 L AMG

The Mercedes R-Class didn’t make much sense in any form. It wasn’t that well packaged and it was ugly, but its interior wasn’t a bad place to be. As a luxury family car for six it was never short of power, but if you wanted an over-abundance of horses Mercedes was happy to sell you a 6.2-litre AMG edition with 503bhp.

That was enough to propel this pricey people carrier from 0-62mph in just 5.1sec, threatening the constitution of its occupants. Just seven are on UK roads, and as a personal statement of otherness there is little to beat it.

There are currently none of these ultra-rare MPV rockets for sale in the UK, but if there were, we imagine they would command over £10k.

Citroën XM V6 24v

Citroën XM V6 24v

The XM was a proper Citroën, with its Hydractive suspension and styling that put it a million miles away from its staid German rivals. Uniquely, when the tailgate was opened a separate hinged window kept rear-seat occupants’ barnets intact.

The XM proved a slow seller and now it’s a bona fide classic it’s the 24-valve V6 that everybody wants. Which is a shame as there are just two left on UK roads.

Want one? You’ll have to venture to continental Europe.

Peugeot 607 V6

Peugeot 607 V6

Anything Citroen could do, Peugeot could match. British buyers don’t like big French cars so when Peugeot introduced the 607 in 2000 it was never going to be a big seller. But it was likeable enough and Peugeot shifted quite a few with four-cylinder petrol and diesel engines.

It was the V6 petrol units that nobody wanted, so it’s a minor miracle that there are still as many as 10 still in use. But what a gloriously comfortable way to get around.

A very respectable looking 2007 model with 72,000 miles with full service history will see you £3,000 poorer but 211bhp better off.

Ford Scorpio TD

Ford Scorpio TD

If ever there was a car perfect for tinted glass it was this one; nobody wanted to be seen driving one. Despite it being one of the most disfigured cars to ever grace our roads there are still dozens of examples still running.But they’re virtually all petrol; just 16 have diesel power. But the thing is vast, with more rear legroom than a contemporary Mercedes S-Class. So bad it’s good?

So good in fact it appears that none of the 16 owners are willing to part with their beloved TDs - none are currently for sale.

Vauxhall Zafira VXR

Vauxhall Zafira VXR

At one end of the motoring spectrum you have the hot hatch and at the other the MPV. One puts driving enjoyment above all else and the other focuses on practicality. We’ll leave you to work out which is which. What you can’t do is combine the two, although that didn’t stop Vauxhall trying with the Zafira VXR.

Some said that it was too much of a sports car ride-wise to make a good family car, and too much of an MPV to be a sporty drive. But we applaud Vauxhall for trying, and it was rewarded with sales. Compared with some in this story there are plenty of survivors – 692 at the last count.

To own one of these seven-seater, 237bhp MPVs you’ll be looking at around £4,000.

Renault Espace Quadra

Renault Espace Quadra

After Germany, Italy and Switzerland, the UK was Renault’s biggest export market for the Espace, and we liked the four-wheel drive Quadra edition so much that it accounted for almost one in six of sales. Admittedly the original Espace is now getting on, but despite its popularity there are just five Espace Quadras surviving on the road here.

To own one, you’ll have to pay around £5,000…and make your way over to mainland Europe.

Seat Altea Freetrack TSI

Seat Altea Freetrack TSI

The picture here doesn’t do the Altea Freetrack any favours as it looks misshapen and frankly more than just a bit weird. But it was actually a pretty decent car thanks to its spacious interior and lengthy standard kit list. But when was the last time you saw one?

Probably never, even though there are more than 400 diesel-powered examples on our roads. Much rarer is the petrol-powered 2.0 TSI, of which there are just 62 currently in use.

We couldn’t find any TSIs for sale at the time of writing, but a decent diesel will cost in the region of £3,500.

Subaru BRZ auto

Subaru BRZ auto

The Subaru BRZ and its cousin the Toyota GT86 prove that you don’t need loads of power to create a brilliant driver’s car. But ideally you do need a manual gearbox, which is why there are just 110 BRZ autos registered in the UK. But if you’re using it for stop-start commuting rather than as a weekend car, it could be for you.

The cheapest automatic BRZ we could find? £13,700.

Vauxhall Vectra 3.2

Vauxhall Vectra 3.2

When Vauxhall introduced a 3.2-litre V6 engine for the Vectra it was always going to be a niche seller. Huge running costs – not least of all depreciation – meant few private punters signed up for one. And neither did fleet managers, terrified of the depreciation rates.

So it was up to police forces to take them on; the 154mph Vectra V6 made a great unmarked traffic car. And a great understated super-wagon for you too, if you give it the chance.

A hefty 750 examples are left, which sounds enormous compared with some we’ve talked about, but that’s down from a cool 4800 in 2005. However, severer depreciation means that we found a 2005 example with 54,000 miles, full service history and one owner from new for just £1,999.

Volvo XC90 V8

Volvo XC90 V8

When Volvo teamed up with Yamaha to develop a petrol V8 it needed to install it into as many of its cars as possible – but only the S80 and XC90 were suitable. Thus equipped, the seven-seat SUV could crack the 0-62mph sprint in just under seven seconds and go on to a limited top speed of 130mph. The original XC90 was a superbly practical seven-seat SUV, and we love the idea of it with a V8.

Miraculously there are more than 160 V8s left on UK roads, many of which we suspect have been converted to run on LPG.

However, we found a good old 4.4-litre petrol with 98,000 miles, full service history and eight months MOT for £9995.

Peugeot 508 RXH

Peugeot 508 RXH

On paper the 508 RXH diesel-hybrid looked promising; 198bhp, four-wheel drive and fuel economy of 69.9mpg. What’s not to love? And for business owners it was even more tempting, thanks to CO2 emissions of just 107g/km.

But the clunky gearbox and fidgety ride conspired to ruin the driving experience, while real-world fuel consumption was closer to 40mpg. Suddenly the 508 RXH wasn’t so lovely after all. Today, 600 examples are left.

We found 2013 reg model with mileage north of 100,000 for £7,200.

Alfa Romeo 166 TS Lusso

Alfa Romeo 166 TS Lusso

When an Alfa dealer sold a 166 there were street parties to mark the occasion; the Italian company just couldn’t tear buyers away from the German brands that ruled the roost. As a result any 166 is now unusual, but if you’ve got one of the 2.0 Twin-Spark Lusso editions you can feel smug knowing it’s one of just 66 or so left on the road.

We found one of those coveted 66 with just 66,000 miles, part service history and five months MOT for £2,999.

Renault Scenic RX4

Renault Scenic RX4

Renault never offered a four-wheel drive version of its later Espaces but it did produce a 4x4 version of the bigger-selling Scenic.

However, the Scenic RX4 didn’t prove a hit and as a result it was short lived. The RX4 featured part-time four-wheel drive with the rear differential displacing the spare wheel well – which is why this was relegated to the outside of the tailgate. Around 300 examples survive across a slightly baffling 16 RX4 derivatives and trims.

You’ll soon find that these soft-roaders can be had for well under £1,000 – we found a decent one for just £650.

Citroen C3 XTR

Citroen C3 XTR

When MG Rover introduced the Streetwise it became the butt of endless jokes, but that didn’t stop Citroën from borrowing the idea and doing its own small hatch-based pseudo off-roader. While Continental buyers could buy their XTR with jacked-up suspension, a limited-slip diff and sump guards, all we got was a lame-looking matt black bodykit. No wonder it sold badly.

However, the endless ridicule has resulted in plenty of sub £1k examples.

Rover 75 Limousine

Rover 75 Limousine

And finally… We imagine that Rover in 2004 would have rather liked then-prime minister Tony Blair to have ditched his Jaguar XJ for one of these long wheelbase 75s. The car even got the 75 V8’s huge front, though sadly not its engine. Rear-seat passengers did however get their own clock. Which is important.

Sadly, Rover only built around 11 examples of these before its future showed up: not a starring role outside 10 Downing Street, but inside it, as Mr Blair wrestled with 6000 Rover staff losing their jobs overnight as the firm keeled over. There are six examples left on UK roads.