The ultra-rare and even more brutal Black Series, launched in 2013, headed up the range with 622bhp and a characteristically imposing bodykit. However, most people can remove this from their watch list because, even when an example does pop up for sale, the asking price is going to be well north of £600,000.

In fact, all variants are holding their value extremely well, to the point that you would have to seriously weigh up the SLS’s investment potential versus its performance capability in light of more modern competition (Lamborghini Huracán Evo RWD for £164,000, anyone?).

The lower end of the market is dominated by early coupés and convertibles, which are harder to sell, due to their lack of gullwing doors. But given prices were topping out at about £100,000 just six years ago, it stands to reason they won’t come back down any time soon. If you have the urge and the means, act now.

How to get one in your garage

An expert’s view

Tom Jaconelli, Romans International: “The SLS is approaching modern classic territory. It came down to about £100,000 in 2014, bottomed out and has since come back up. There’s a big price difference between top-spec, low-mileage examples – some people want £180,000-£200,000 – compared with those with 30,000 miles, which you could get for £115,000-£120,000. That’s because collectors are looking for ‘the ultimate one’. A Black Series will be more than double that, and the Final Edition, which barely ever comes to market, is £300,000-£400,000.”

Buyer beware…

■ Engine: The bespoke V8 is highly strung but robust and dependable. Just be ready to average only 15mpg in daily driving. Expect to pay around £500 for an A service and up to £1000 for a more comprehensive B service. Change the oil and oil filter every 10,000 miles.

■ Gearbox: The Getrag dual-clutch seven-speed automatic gearbox was lambasted for slow shifting in pre-2012 cars, so Mercedes offered a free software update in 2013; check this has been carried out. It’s also worth noting that most specialists view the gearbox as a sealed unit, so any faults generally result in total replacement, with a long wait while a new unit is built to order.

■ Bodywork: High purchase and maintenance costs mean the SLS is customarily driven and stored carefully, but it’s still worth poking around underneath for scrapes and signs of accidents. The gullwings open wide so are easily damaged on adjacent cars and walls, so check the bottom edges for scratches. Make sure the convertible’s roof opens and shuts smoothly and firmly in 11 seconds.

■ Tyres: Rubber doesn’t usually live for long on the SLS, given its propensity for powerslides and 1620kg kerb weight. New tyres are easy to find, but budget around £250 per corner for Michelin Pilot Sport or Pirelli P Zero items and rotate them every 5000 miles.

■ Brakes: Carbon-ceramic brakes are highly sought after and were often specified despite being one of the priciest options. They substantially strengthen stopping power and weigh 40% less than the standard brakes, but some find them too hardcore for regular use, and a replacement set of calipers and discs will set you back at least £8000.