The SLK was the German brand’s baby roadster with a 5.5-litre V8 under its bonnet
From the roar of its V8 to its long-nosed looks, there are plenty of reasons to shoot for the small yet mighty SLK
The Mercedes-Benz SLK 55 AMG is like a squirrel wielding a hand gun: so small yet so powerful.
What we have here is the German brand’s baby roadster (in R172 guise) that, as if by magic, has had a 5.5-litre V8 engine squeezed under its bonnet. It’s a unique and captivating proposition, yet one that’s actually rather affordable.
And we don’t just mean to buy, either, because its engine made this SLK the most fuel-efficient V8-powered production car in the world upon its debut. This is thanks to engine stop-start system, high-pressure direct injection, intelligent ancillary power management and clever cylinder deactivation tech.
It emits 195g/km of CO2 and averages 33.6mpg officially. As a result, you won’t pay extortionate amounts in fuel or tax, the latter of which comes in at £330. Without such reasonable running costs, the SLK 55 would likely be confined to weekend toy duties, but no, this hot rod can be a viable daily driver – more so than its R171 predecessor.
If you’re not in the mood to be sensible, though, there’s still 416bhp and 398lb ft of torque beneath your right foot. This roadster’s 0-62mph time of 4.6sec won’t be enough to scare the latest super-hatchbacks, like AMG’s own Mercedes-AMG A45 S, but it remains enough to properly push you back into your seat. What’s more, you will be hard pressed to find a hatch that can rival the SLK 55’s savage exhaust note.
This makes it irresistibly exciting to rev out to 7200rpm – and you best have that electrically folding metal roof down when you do.
On the other hand, you can really access its grand touring abilities with the roof up. This little two-seater may not have Mercedes-Benz S-Class-grade suspension, but the ride is compliant enough that long distances can be covered with ease.
It must be said that the SLK 55 isn’t the sharpest tool in the shed when it comes to handling. After all, it weighs a lot for its size: it tips the scales at 1610kg, in fact. Those wanting a more polished drive should still look to its closest rival – the Porsche Boxster – although that’s significantly less powerful.
The Mercedes is the hammer to Porsche’s scalpel. It’s brutish and incredibly thrilling to hustle down the road. It tells you to hang on and enjoy the ride, rather than giving you the utmost engagement and adjustability through bends.
Another aspect that reinforces this is the lack of a manual gearbox option. In typical Mercedes fashion, the SLK 55 is automatic-only, having a seven-speed torque-converter with shift paddles on the steering wheel.
Thankfully the brakes are strong, and if your car has the optional Handling Pack fitted, you will find it has some go-faster goodies including a limited-slip differential. Considering the power it has to deal with, seeking out such an example could be well worth it.
So now you know that the SLK 55 is fast, sonorous, luxurious and surprisingly cheap to run, but how much will it cost you to buy? Well, less than £30,000 in most cases. For what you’re getting, that’s not a lot to stomach. And its rarity (we found fewer than 20 for sale) combined with the intrigue of having such a big engine in such a small car means it’s sure to be a good investment.
What we said then
14 November 2011: “If you like the idea of big, open-air performance without the usual penalty of sub 25mpg fuel economy, [buy an SLK 55]. The virtues of AMG Mercs often take longer than the usual test route to present themselves to the driver, and it’s very possible that this SLK would wind up being a highly satisfying car to own for all sorts of reasons.”
An expert’s view
Adam Franks, Project AMG: a large engine is pretty cool. The engine’s cylinder shut-off function was quite advanced for its era and the technical highlight. These cars are pretty bulletproof from the engine and transmission perspectives; we don’t hear too many nasty stories. One thing that has recently come into play is corrosion on the rear axle and brake lines. When you drive it, note any engine vibrations or things like that, because they’re telltale signs that the car has been driven hard and the engine mounts are a bit tired. The heart of the engine will be absolutely fine, though. It can take quite a lot of abuse, really.”
Body: The divider between the home of the folding metal roof and the luggage space needs to be locked in order for the roof to lowered, and it can be insecure, with latches that don’t seat in the catch very well. This can cause the roof to jam both when open and closed.
Test that the roof operates flawlessly before you buy any car, as it won’t be a cheap thing to fix. Stone chips are common, so it’s worth going over the paintwork with a fine-tooth comb. Do the same with the alloy wheels, checking for any kerbing – especially larger scuffs, which could indicate knocked suspension or wheel mid-alignment.
For a performance car with hefty power going through the rear wheels alone, the tyres need to be up to the task, and new ones can be expensive. – around £330 for a pair from a premium brand. So when you buy a car, check what tyres are on it and how much life they have left in them.
Electrics: Some owners report electrical issues, such as the air conditioning’s control unit not turning on after jump starts. The cause could be as simple as a fuse, but it could be worth getting a scan done by a Mercedes specialist to properly diagnose the problem.
Interior: Water can leak into the boot, due to the folding metal roof mechanism, so it’s worth making sure there’s none in the boot and that no areas inside the car feel damp.
If the SLK 55 you’re looking at has Mercedes’ Airscarf (a system that channels warm air onto the necks of the driver and passenger), make sure that it still works as intended, as some owners have reported it failing.
Chassis: Check for corrosion on the rear axle and brake lines, which are becoming common problem areas as these cars age. If it’s excessive, avoid. A new set of lines should cost you about £100.
Also worth knowing
The SLK 55 AMG was succeeded by the AMG SLC 43 in 2016. The V8 was ditched in favour of a turbocharged 3.0-litre V6, perhaps unsurprisingly. With less power than its predecessor and no muscle-car-esque exhaust note, the SLC 43 was felt by many people to be a downgrade. It was discontinued in 2018.
How much to spend
£20,000–£24,999: Early examples in generally good conditions with mileages of around 50,000, sold by private and independent dealers.
£25,000–£29,999: Mileages often drop to less than 30,000 here and higher specs are present. Some later cars.
£30,000 and above: Late cars in showroom condition with mileages of around 20,000.
One we found
Mercedes-Benz SLK 55 AMG, 2013, 26,000 miles, £28,480: This SLK 55 AMG has a relatively low mileage and a good-looking spec. It has red nappa leather upholstery and 10-spoke AMG wheels. It also has a full Mercedes and specialist dealer service history. It’s being sold by an independent dealer.