Buyer’s Guide Mercedes-Benz SLK320 R170

Buyer’s Guide Mercedes-Benz SLK320 R170

When new, the first generation SLK mesmerised with its seductive looks, vario-roof arrangement and sporty handling, and now you can pick one up for just a few thousand pounds. Words David Sutherland. Images Terry Oborne & Daimler AG.

Bargain roadster — V6-powered R170 SLK320 inside and out

With its super stylish, compact body, amazing folding metal roof system and a price that was affordable by Mercedes-Benz roadster standards, the original R170 SLK was no less than a sensation when launched in late 1996. The ‘junior’ SL instantly hit the spot, dealers needing to do little more than sit back as orders poured in and delivery queues lengthened; in the early months of production, cars in the UK changed hands for over the list price of £29,000, even against a quite generous supply from Stuttgart, some 2,400 delivered in the UK in its first full year on sale (twice the SL volume), sufficient for it to out-sell the Porsche Boxster 986 and Toyota MR2 combined.

Buyer’s Guide Mercedes-Benz SLK320 R170

For its vario-roof alone, the SLK (‘K’ for ‘kurz’, or ‘short’) was an engineering marvel. The roof was the first of its kind in the modern era and collapsed into the boot in 25 seconds, turning a cosy coupe into a full, no compromise open roadster, and with pop-up rollover protectors. A joint venture company, Stuttgart-based CTS GmbH (Car Top Systems) had even been established to make the roof. And inside, the SLK was a delight: well-built and an appealing combination of a modern design but with some retro detailing such as sunken instrument dials.

Yet it arguably did have one weakness – the engine. Mercedes-Benz offered only four-cylinder units, the principal model the SLK230 Kompressor using the then new M111 supercharged 2.3-litre four-cylinder unit producing 190bhp, and 207lb ft torque. This, in five-speed automatic form was the sole model for the UK, and the powerplant was the R170’s least likeable aspect; powerful enough but unrefined and gruff sounding. Mercedes management claimed a six-cylinder model was not necessary as customers would be happy with the four-cylinder engine. However, that mindset changed when at the facelift the normally aspirated 3.2-litre V6 SLK320 was added to the range.

Production of the R170 ceased 17 years ago, to make way for the more aggressively styled R171, and while the series is showing a glimmer of collectability, this is still a cheap Mercedes-Benz roadster. There are still quite a few SLK320s around for sale, prices ranging from £2,000 to £10,000, so how does it differ as an ownership prospect to the SLK230 K R170?

Design & engineering

The SLK was based on a C-Class platform, its styling overseen by legendary Mercedes designer Bruno Sacco in his final years at Mercedes-Benz, and was notable for its short overhang and clipped tail. It was not intended to be a ‘proper’ sports car, more a tourer and hence with quite soft chassis settings including Mercedes’ traditional recirculating ball steering that prioritised shock absorption over feedback.

For the four years from launch to the February 2000 facelift, the SLK ran unchanged, save a few specification tweaks. Aesthetically, the revamp saw Mercedes’ usual type of mid-term updates, including restyled front and rear bumpers, new sill trims, painted radiator grille and stainless steel exhaust tips, while the side indicators were moved from the wings to the door mirrors.

Inside, the original carbon look gave way to aluminium style trim, the steering wheel was redesigned and wood trim became an option for the first time on the SLK.

However, the standout aspect of the mid-term revamp was the arrival of the SL320 using the M112 three-valves-per-cylinder V6 already in other models, and giving 215bhp at 5,700rpm and 227lb ft torque at between 3,000 and 4,000rpm.

A six-speed manual gearbox was offered for the first time on UK-bound SLKs, including on the V6 car. Wheels were 16-inch alloy with 205/55 front and 225/50 rear tyres; 17s were optional and many 320s have them.

From then until the end of production there were no engineering or aesthetic changes, but – perhaps with customer demand not quite as hot as it had been at first – there were two limited editions of the SLK320 (and also the 230) released in that period. The first came in June 2002, the SLK320 Limited Edition which was equipped with 7.5Jx17-inch Evolution alloy wheels, black nappa leather, brushed aluminium interior trim and a silver instrument panel with white dials.

The second came as the R170 was in its run-out stage, in January 2004. The SLK320 Special Edition featured a chrome grille and bootlid handle plus bright polished exterior trim strips, and again nappa leather trim, including on the rollover bars; these cars are identified by the ‘SLK Special Edition’ badges on the wings.

Driving the SLK320 R170

The SLK320 brought a new dimension to the R170 range. It’s not much quicker than the SLK230, but the normally aspirated V6 is so much sweeter and smoother than the four-cylinder, and is well suited to the manual six-speed gearbox, its shift a big improvement over previous manual Benz ’boxes. Handling is comfort, not sports oriented, with shock-free but largely uncommunicative steering, and soft springing that aides ride comfort but allows the Mercedes to roll somewhat through corners.

The cabin is a tight fit for occupants and with a high door line you can feel closed in. But the driving position is perfect and the seats supportive, and oddment space is good, including a decent glovebox despite the presence of a passenger airbag. The facia was an interesting design given the blandness of many late 1990s Merc interiors, and the switchgear feels solid, the SLK cabin thus retaining the quality feel that some Mercedes models were about to lose. Most SLK320s have leather, which adds to the ambience.

What you’ll pay

The SLK320 appears to command a small price premium over the 230, but you will still see cars for £2,000 or less. But the usual rules regarding false economy apply and we recommend regarding £4,000 as the sensible entry point for a car free, or largely free, of problems. The most common price for 320s is between £4,000 and £5,000, this bracket offering cars from both private sellers and used car dealers.

An SLK in exceptional condition and with low mileage is going to cost up to £10,000. We saw one such example, a 2003 car with 32,000 miles in silver over red leather offered by Kingdom Specialist Cars in Hampshire, asking price £9,500.

It’s not a car that tended to rack up high mileage, often a second one in the household, so you’ll see plenty with moderate mileage, between 50,000 and 70,000. When looking for an SLK320, it’s worth noting that all but the very earliest examples are EU4 rated emissions, thus avoiding the extra charge for London’s Congestion Zone and others to come.

Just the facts Mercedes-Benz SLK320 (R170)

  • ENGINE M112 3,199cc V6
  • MAX POWER 215bhp @ 5,700rpm
  • MAX TORQUE 227lb ft @ 3,000-4,800rpm
  • TRANSMISSION 6-speed manual/5-speed auto, RWD
  • WEIGHT 1,405kg
  • 0-62MPH 6.9sec
  • TOP SPEED 152/150mph
  • FUEL CONSUMPTION 25.5/27.1mpg
  • YEARS PRODUCED 2000-2004

All figures from Mercedes-Benz; fuel consumption according to NEDC Combined

R170 SLK320 Inside and out


  • If you see oil on the ground underneath the car, it will almost certainly be from the engine rocker covers or the oil filter housing. In both cases the cure is a simple gasket/seal change.
  • The water pump can eventually give trouble. You’ll hear it becoming noisy and it will leak out some fluid, and eventually the engine coolant level will fall and cause overheating.
  • A failed engine crank position sensor will make the engine difficult or impossible to start when hot. This is a relatively cheap fix and can almost be considered preventative maintenance; it’s a very common fault on Mercs with this V6.
  • The automatic gearbox sensor plate can fail, trapping the transmission in ‘limp home’ mode. However, the five-speed’s plate is less complex than that in the later, seven-speed ’box and at around £500 replaced is a much cheaper fix too.

V6 trumps the four-cylinder for smoothness and sounds fantastic; SLK320 offered with a two-mode auto or manual.

Specialist overview Steve Dickens, Autoclass Garage, Milton Keynes

“Good news – the M112 V6 has proved to be bulletproof. It’s very reliable, much more so than the four-cylinder Kompressor engines and we don’t do very much to them.

The M272 V6 that was installed in the 2004-on R171 equivalent, the SLK350, is far more powerful but not nearly as reliable.

“The main requirement on the SLK320 is to keep on top of oil changes, so look for a full service history. Most cars are automatics, the manual being very rare – I’ve only ever worked on a couple of them.”

Suspension, steering and braking system

  • There are no chassis electronics, so little to go wrong. However, mileage and sheer age can take their toll on the suspension, so ideally get the car on a ramp for checks on ball joints, bushes and related components. Particular attention should be paid to the subframe bushes, because if these require changing, it’s at least a day’s work for a garage to replace all four.
  • A ‘wandering’ or vibration in the steering usually means the steering damper is worn out. Dampers normally require replacing at around 100,000 miles or 10 years and are relatively cheap and return some steering feel.
  • Brakes should feel powerful and free of vibration through the pedal. Make the usual checks for the remaining life of the brake discs; the bigger the lip on the outer edge of the disc, the less time it has left.

Mercedes made 33,416 examples of the SLK320 between 2000 and 2004.

Bodywork and wheels

  • R170s can be quite rusty, especially around the wheelarches. Corrosion also attacks the underbody, but you will have to raise the car on a ramp to spot this. By now, some SLK320s will have body filler concealing rust.
  • Even though the roof is complex, with many switches and sensors, it has proved remarkably reliable. Nonetheless, it’s crucial to check it operates correctly: it should lower and raise smoothly and quietly in 25 seconds, and if it lets water in this could require the replacement of seals, which are not cheap.
  • Some models wear alloy wheels with a high gloss, ‘diamond cut’ finish. The lacquer peels off all too easily, so budget for refurbishment back to the same finish if this is the case.

During development, the R170 was tested in Death Valley and around the Pico Veleta in Spain; roof opens and closes in 25 seconds. New seat suspension was developed for the R170; ASR and ABS fitted as standard; ivory coloured dials a nod to SSK and SSKL.

A failed engine crank position sensor will make the engine difficult or impossible to start when hot

Interior and electrics

  • The pump which supplies vacuum power to operate the door locking can be problematic. This is due to its location deep in the spare wheel recess, water in this area causing the pump to fail, and the electrics to fail. But it’s easy enough to check if the pump is in good order – if the door locking works, it is.
  • If a rear light bulb has failed, a new bulb holder or even a complete new lamp may be needed.
  • Although the SLK’s interior was made to a superior standard than some other Mercs of the same years, the interior can now look worn. The trim plastics have a coating which can peel off, and broken indicator stalks are common.


The R170 SLK was the most practical ‘small’ roadster of its day, and even now remains a car that is fun and useful in equal measure provided you need only two seats. It also has its own charm among the three model generations, many liking it for it being the most pure and simple in appearance.

Is the SLK320 better than the 230 Kompressor? Its on-paper performance is little different, and it lacks the supercharged four’s mid-range punch. But it brings the six-cylinder refinement many seek in a Mercedes. Auto or manual? The majority are the former, so if you want to swap gears yourself you won’t have such a wide choice. However, the most important consideration is the car’s overall condition, given that the early ones are now over two decades old. As we’ve said, rust is now a major problem and isn’t always easy to spot. So, we would recommend paying more for a better car, especially as when these Mercedes eventually become viewed as classics, the best examples will be in most demand.

Thank you, Mazda MX-5!

Mercedes’ inspiration for the original SLK came from an unlikely source – the Mazda MX-5. The affordable Japanese two-seater, launched in 1989 as a Lotus Elan for the modern world, had been a major hit, finding 70,000 homes per year by 1991, proving that the market for such a model had not died with 60s sports cars. Mercedes-Benz planners had in fact been considering a small and civilised roadster since the late 1980s – but the popularity of the Mazda hastened Stuttgart’s re-entry to the niche it had all but created with the 1955 190SL W121 BII, but then gradually let go of as subsequent SLs grew in size. There were understandable questions over whether such a roadster would steal sales from the R129 SL, and could be built cheaply enough to still yield a profit given that it would have to be priced much lower than the SL. But the car maker took a chance and scored a major success, the SLK a popular model for the next 25 years.

Typical basic servicing costs (A/B services including VAT)


Quotes from Autoclass Garage Non routine servicing costs

★ Replace leaking gaskets on engine rocker covers £185

★ Replace engine water pump £425

★ Renew failed automatic gearbox sensor plate £495

★ Fit new engine crankshaft position sensor £225

★ Fit new front brake discs and brake pads £280

★ Install replacement folding roof seals £1,200

★ 4x premium tyres, 225/45R17 (F), 245/40R17 ® £400 S

LK320 timeline

  • January 2000 The R170 received its mid-term facelift, at which point the SLK320 was added to the range and offered with a five-speed automatic or six-speed manual gearbox
  • June 2002 SLK320 Limited Edition with 7.5Jx17-inch wheels and special trim was introduced
  • January 2004 The run-out SLK320 Special Edition arrived at dealers, with nappa leather upholstery and special trim
  • June 2004 R170 production ceased, replaced by the R171 SLK series

What you’ll pay

£1,000-£2,000 Early SLK320 cars, with rust and mechanical issues, best avoided

£2,000-£3,000 Probably a good runner but in need of quite a lot of tender loving care!

£3,000-£4,000 Sound example, but will most likely have covered near or over 100,000 miles

£4,000-£5,000 This is the main price bracket for an SLK320 with under 100,000 miles

£5,000-£6,000 Late examples, above average condition, with under 70,000 miles

£6,000-£10,000 For this money, it must be pristine and with low mileage and a comprehensive history

Spotted for sale


SLK320 2000/W, manual, designo purple, black/purple leather, AMG alloys 50,100 miles, £9,950, Hampshire



2002/02, automatic, silver, black leather, three months warranty, 40,000 miles, £5,995, Peterborough



2003/03, automatic, silver, black leather, 17-inch alloys, 78,000 miles, £3,995, Colchester, Essex

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