Mercedes-Benz SLK R170 buyer's guide

The first Mercedes-Benz SLK, internal code R170, is a compact two-seat roadster with an electrically operated folding steel roof that Mercedes called the Vario roof. At the press of a button it turns a snug coupe into an open car in under half a minute, and it did much to start the fashion for folding hardtops. The name stands for sportlich, leicht und kurz: sporty, light and short.

People buy one for its all-weather practicality, solid feel and strong supercharged and V6 engines. The weak points are well known: rust in the arches, wings, sills, boot lid and rear subframe, a hydraulic roof that suffers from neglect, and oil or water getting into the electrics.

This guide is for buyers at a dealer, privately or at an auction such as Mathewsons in North Yorkshire, and for owners preparing to sell. It covers what to check, not how to repair it.

By Jon Cosson · Checked 20 October 2026

At a glance

Built	1996 to 2004, replaced by the R171
Concept	Shown as a concept at the 1994 Paris Motor Show
Numbers made	More than 300,000
Body style	Two-seat roadster with electro-hydraulic folding steel Vario roof
Platform	Shortened version of the W202 C-Class underpinnings
Four-cylinder engines	2.0 naturally aspirated (some markets), 2.0 Kompressor and 2.3 Kompressor, all M111 family
Six-cylinder engines	3.2 V6 (SLK320) and supercharged 3.2 V6 (SLK32 AMG), M112 family
Gearboxes	Five-speed manual, six-speed manual after the 2000 facelift, five-speed automatic
Facelift	2000: new bumpers, body-coloured side skirts, indicators in the door mirrors
Typical use	Year-round roadster, summer weekend car, entry to Mercedes ownership
Club	Mercedes-Benz Club (UK)

The Mercedes-Benz SLK (R170): SLK200, SLK200 Kompressor, SLK230 Kompressor, SLK320, SLK32 AMG in brief

Mercedes showed the SLK as a concept at the 1994 Paris Motor Show and the production car went on sale in 1996, reaching UK buyers later that year. It was the company's first hardtop convertible, a rival to the Porsche Boxster and BMW Z3, and it used a shortened version of the W202 C-Class floorpan and running gear, so many mechanical parts are shared with the C-Class of the same era.

The UK launch car was the SLK230 Kompressor, with a supercharged 2.3 litre M111 four-cylinder of about 190bhp and 0 to 60mph in a little over seven seconds. A naturally aspirated 2.0 litre SLK200 of about 136PS and a supercharged SLK200 Kompressor were sold in some other markets.

The roof is the defining feature. A hydraulic pump in the boot drives rams in the roof and boot lid, and microswitches tell the control system where each part is in the sequence. The windows drop automatically. In good order the roof opens or closes in around 25 seconds, and folded it takes up much of the boot.

The 2000 facelift brought restyled bumpers, body-coloured side skirts in place of black ones, indicators in the door mirrors, revised trim and seats, a six-speed manual gearbox and revised suspension. The SLK200 Kompressor became widely available at about 163PS, and the SLK320 arrived with a 3.2 litre V6 of about 218PS.

In 2001 came the SLK32 AMG, with a supercharged, intercooled 3.2 litre V6 of 354PS (about 349bhp), 0 to 62mph in around five seconds and a five-speed automatic gearbox. It is the rarest and most sought-after R170. The R171 replaced the range in 2004.

Late 1990s Mercedes build quality was weaker than in earlier decades and the steel rusts readily. Specialists agree that body condition matters more than which engine a car has. Later cars are generally less rot-prone, but none is immune.

Versions to know

Version	Years	What to know
SLK200	1996 to 2000	Naturally aspirated 2.0 litre of about 136PS, sold in some markets. Rare in the UK.
SLK200 Kompressor (pre-facelift)	1996 to 2000	Supercharged 2.0 litre for markets that taxed engines over two litres heavily. Uncommon in Britain.
SLK230 Kompressor (pre-facelift)	1996 to 2000	The launch car and the most common R170 for sale. About 190bhp, five-speed manual or automatic. Black side skirts and wing-mounted indicators.
SLK200 Kompressor (facelift)	2000 to 2004	Supercharged 2.0 litre of about 163PS. A little less brisk than the 230.
SLK230 Kompressor (facelift)	2000 to 2004	Facelift styling and trim, six-speed manual option, about 194bhp.
SLK320	2000 to 2004	3.2 litre V6 of about 218PS, six-speed manual or automatic. Manual V6 cars are unusual.
SLK32 AMG	2001 to 2004	Supercharged 3.2 V6 of 354PS with AMG bodywork, wheels, brakes and suspension, five-speed automatic. The rarest version; demands the strongest history.

Pros and cons

Pros	Cons
Folding steel roof gives a secure coupe in winter and an open car in summer Supercharged and V6 engines are strong and durable when serviced Comfortable ride and a stiff body Many mechanical parts shared with the W202 C-Class Large numbers built, so buyers can be choosy Good network of independent Mercedes specialists SLK32 AMG offers serious performance	Rust in arches, wings, sills, boot lid, floors and rear subframe is common Roof hydraulics, switches and seals suffer from neglect and can be costly to put right Oil can travel along wiring into engine and gearbox control units Water leaks can upset central locking and other electrics Little boot space with the roof folded Less sharp to drive than a Boxster or MX-5 Flaking soft-touch coating on interior plastics

Pros

Cons

Folding steel roof gives a secure coupe in winter and an open car in summer
Supercharged and V6 engines are strong and durable when serviced
Comfortable ride and a stiff body
Many mechanical parts shared with the W202 C-Class
Large numbers built, so buyers can be choosy
Good network of independent Mercedes specialists
SLK32 AMG offers serious performance

Rust in arches, wings, sills, boot lid, floors and rear subframe is common
Roof hydraulics, switches and seals suffer from neglect and can be costly to put right
Oil can travel along wiring into engine and gearbox control units
Water leaks can upset central locking and other electrics
Little boot space with the roof folded
Less sharp to drive than a Boxster or MX-5
Flaking soft-touch coating on interior plastics

Myths and realities

The Vario roof is a disaster waiting to happen.

It is generally reliable when used regularly and kept topped up with the correct fluid. Most faults come from neglect: seized microswitches, old fluid, leaking rams or water damage.

Mercedes quality means it will not rust.

Late 1990s Mercedes steel and paint were not up to earlier standards. Every R170, including late ones, needs a careful rust check.

The automatic gearbox is sealed for life.

Specialists recommend an oil and filter change at around 35,000 to 36,000 miles.

A noisy supercharger is normal.

A loud or continuous whine or rattle can point to a supercharger on its way out.

What to check

Bodywork and structure

Rust is the single most important issue on any R170. A sound body is worth more than a particular engine, low mileage or a long equipment list.

All four wheel arches: look for bubbling on the lips and feel inside the rear arches, where scabs hide worse rot.
Front wings along the edges, at the base where they meet the sills and around the lights. On pre-facelift cars rust forms behind the wing-mounted indicator lenses.
The full length of the sills and the sill ends.
Boot lid around the handle and keyhole above the number plate, and along the lower edge.
Bonnet leading edge and power domes, where stone chips start corrosion.
Screen pillar tops and around the windscreen.
Floors and rear subframe, which can be badly corroded and are hard to see; read the online MOT history for advisories.
Front coil spring top mountings, which can rust and in extreme cases fracture.
Past repairs: overspray on lights, trim and side skirts, ripples or filler. Poor repairs can bubble again within months.
Panel gaps around the bonnet, boot lid and doors.

Vario roof hydraulics and sensors

The roof is what most buyers are paying for, so test it thoroughly and be wary of any seller who will not demonstrate it.

Operate the roof several times with the engine running. It should open and close smoothly in around 24 to 30 seconds, windows moving automatically. A slow cycle can mean low fluid or leaking hydraulics.
Watch the whole sequence: boot lid lifting, roof folding, boot lid closing and locking. Any pause or jerk needs investigating.
Nine microswitches in the roof and boot lid confirm each stage. They can seize on cars whose roof is rarely used, and a faulty switch can stop the cycle and be mistaken for a hydraulic fault.
The pump sits on the right of the boot. Look for fluid leaks around it and check the reservoir; dark fluid suggests it has never been changed.
The roof rams and two boot lid rams can leak. Headlining stains may come from leaking cylinders as well as water.
Listen for groaning or straining from the pump and squeaks from the linkages and seals.
Check the roof seals for splits and flattening, and the linkage joints for rust.
Treat a car with an inoperative roof with great caution: the cause may be simple or several components.

Engine and supercharger

All the engines cover high mileages with regular oil changes, but each has specific points to check.

Look for regular oil changes; the timing chain and the supercharger both depend on clean oil.
Kompressor engines: listen for a loud or continuous whine or rattle from the supercharger and check the car pulls strongly through the rev range.
Camshaft adjuster magnet: oil can leak into its plug and wick along the loom to the engine control unit, causing warning lights or poor running. Look for oil in the connector and ask whether the revised parts are fitted.
Oil leaks around the camshaft adjuster on facelift cars, and coolant loss from the radiator or water pump.
Four-cylinders: clogged breather flame traps and faulty air mass meters are known issues; a shaking idle suggests worn engine mounts.
Noises at idle can come from the timing chain tensioner, clutch or loose exhaust heat shields.
V6: robust, head gasket failure is rare. Twelve spark plugs and four catalytic converters, so check plug changes and for exhaust blows.
SLK32 AMG: insist on a full, recent specialist history.

Gearbox and drivetrain

Manual gearboxes are durable. The five-speed automatic is good when maintained but has known weak spots.

Automatic: shifts should be smooth and prompt. Jerky, delayed or harsh changes are warning signs.
Ask whether it has stuck in gear or gone into limp-home mode. Causes include a failed speed sensor, a faulty multi-pin connector or low fluid.
Oil can leak along the gearbox wiring at the connector and reach the transmission control unit. Look for oil there.
Inspect the automatic's oil cooler pipes for corrosion and leaks.
Ask for evidence of an oil and filter change at around 35,000 to 36,000 miles.
Manual: listen for whine, check synchromesh and feel for clutch slip or pedal box play.
Check the rear differential for oil leaks.

Suspension, steering and brakes

The C-Class based running gear is tough, but age and neglect show in a few predictable places.

Front lower ball joints are a common failure; listen for clunks over bumps.
Rear springs can snap at the bottom coil; listen for thumps and check ride height.
A persistent rear squeak is more likely dried-out bushes.
Check dampers for leaks and bushes for wear.
Brake pipes corrode and calipers seize on little-used cars.
ABS and traction control lights should come on with the ignition and go out.
Look for corroded alloy wheels and cheap mismatched tyres.

Electrics and instruments

Most R170 electrical faults trace back to water or oil getting where it should not, so look for the cause as well as the symptom.

Test every switch: windows, mirrors, locking, heater fan, lights, wipers, horn, radio and roof.
Water in the boot can damage the pneumatic central locking pump. Lift the boot floor, look for damp, and check locking on doors and boot.
Damp boot carpets are often caused by blocked drain holes.
Under the bonnet, look for water around the control module, relays and fuse box, a source of intermittent faults.
Indicator faults can come from dirty bulb holders or the control module; early cars can have a sticking flasher relay.
Check every rear lamp, including both number plate lights.
The engine warning light should light with the ignition on before starting. If not, ask why.
Ask whether a specialist has read the stored fault codes recently.

Interior and trim

The cabin wears reasonably well, but some materials age badly and water leaks show up here first.

The soft-touch coating peels around the handbrake, console, seatbelt buckles, handles and door cards, looking shabby on lighter interiors.
Check seat bolsters and carpets for wear.
Look for water stains on the headlining, carpets and seat bases.
Check headlamp lenses for fogging.
Listen for squeaks from the roof seals with the top up.

Paperwork and originality

A thick folder of invoices on an R170 is worth a great deal, because it shows whether the known faults have been dealt with.

Check the V5C, VIN and engine number against the car and the claimed model.
Read the online MOT history for corrosion, subframe, spring mount, brake pipe and ball joint advisories, and mileage gaps.
Look for invoices for roof fluid changes and repairs, gearbox servicing and camshaft magnet work.
Rust repair invoices should say what was done and by whom.
Confirm an SLK32 AMG is genuine; badges, bumpers and wheels are easy to swap.
Note modifications such as aftermarket wheels, lowered suspension or remaps.
Check for spare keys, service book and owner's manual.

On the test drive

Start from cold if you can, listening for chain rattle and supercharger or heat shield noise.
Watch the engine, ABS and traction control lights go out.
Run the roof several times before and after the drive, timing it.
On a Kompressor, accelerate firmly and feel for strong, even pull.
On an automatic, check smooth changes and prompt kickdown when warm.
On a manual, check for crunching changes and clutch slip.
Drive over bumps listening for ball joint clunks and spring thumps.
With the roof up, listen for wind noise at speed.
Afterwards, look underneath for fresh oil or fluid leaks.

Buying at auction

Plenty of R170s pass through UK auctions such as Mathewsons in North Yorkshire. You will usually buy with fewer checks than in a private sale, so use the viewing days well.

What you can check in viewing week

Use a torch under the car for the sills, floors, rear subframe, spring mounts and brake pipes.
Run a magnet over the arches, sills and lower wings to find filler.
Check the VIN and engine number against the V5C.
Check oil, coolant and roof fluid levels and condition.
Lift the boot floor and look for damp and leaks around the roof pump.
Look for oil in the camshaft magnet and gearbox connectors.
If staff allow, start the engine and operate the roof.
Read the paperwork and the online MOT history.

What you usually cannot do

You usually cannot drive it, so the gearbox, suspension and supercharger under load stay unknown.
You usually cannot lift it, so the subframe and floors are only partly visible.
The roof may not be demonstrated.

Tips

Read the catalogue critically: roof not tested or sold as seen leaves the risk with you.
A buyer's premium, plus VAT on it, is added to the hammer price. Check the terms first.
Set your limit beforehand, allowing for premium, transport and likely work, and stick to it.
Do not be swayed by low mileage alone.
Arrange transport home, or drive it only if taxed, insured and with a current MOT.

What makes one more desirable

A rust-free body with documented repairs counts for more than anything else.
A fully working roof with a record of fluid changes.
Full service history from dealers and specialists.
The SLK32 AMG is the rarest and most sought-after version; the SLK320 suits buyers wanting a V6.
Facelift cars are generally preferred for looks.
Automatic gearbox and leather interior are the most popular specification; traditional colours appeal more widely than bright ones.
Original, unmodified condition and believable mileage backed by the MOT history.

This guide does not give values or predict prices.

Selling a Mercedes-Benz SLK (R170): SLK200, SLK200 Kompressor, SLK230 Kompressor, SLK320, SLK32 AMG

Buyers know about rust and roof faults, so a frank description backed by evidence sells an SLK faster than a glossy one.

Preparing the car

Make sure the roof works smoothly; sort any slow or faulty stage first.
Deal with rust properly or describe it honestly.
Dry the boot and clear the drain holes.
Fix warning lights and check every electrical function works.
Clean the car thoroughly, including the underside and engine bay.

Paperwork

Gather the V5C, service book, invoices and old MOTs in date order.
Highlight roof, gearbox, rust and camshaft magnet work.
Include both keys and the manual, and have a current MOT.

Where to sell

Classic and enthusiast classified websites and magazines.
Mercedes-Benz Club classifieds and forum.
A specialist Mercedes dealer.
Auction houses such as Mathewsons, especially for a well-documented car or an AMG.
General online marketplaces.

Writing the description

State the model, year, engine, gearbox and whether pre or post facelift.
Describe the roof honestly, including fluid changes and work done.
Photograph the arches, sills, boot lid, underside and interior clearly.
List known faults, the mileage and the number of owners.

Living with one

Many mechanical parts are shared with the W202 C-Class and remain widely available, new and used.
Independent Mercedes specialists cost less than dealers and know the common faults.
Use the roof regularly and keep its fluid fresh; lubricate the linkages and seals.
Keep the drains clear and check the boot floor for water.
Wash the underside and arches after winter to slow rust.
Diagnostics may need specialist equipment rather than a basic code reader.
The earliest cars reach 40 years old in 2036, so none yet qualifies for historic tax or MOT exemption.
Agreed value, limited mileage classic insurance is available for many cars.

Clubs and registers

Mercedes-Benz Club (UK)

Questions people ask

What are the most common problems with the Mercedes SLK R170?

Rust in the arches, wings, sills, boot lid and rear subframe; roof faults from leaking hydraulics, old fluid and seized microswitches; oil wicking into control units; water damaging the central locking pump; front ball joints and broken rear springs.

How long should the SLK roof take to open?

Around 24 to 30 seconds. Slower operation, pauses or jerks suggest low fluid, leaking rams, a tired pump or a faulty switch.

Which SLK R170 should I buy?

The best body you can find matters more than the engine. The 230 Kompressor is the most common, the 320 smoother, and the SLK32 AMG much faster and rarer but needs a strong history.

Is the SLK R170 reliable?

Mechanically it is generally robust if serviced. Most problems come from rust, roof neglect and water or oil in the electrics.

Is the Kompressor supercharger a weak point?

Not usually, if oil changes have been kept up. A loud whine or rattle, or lost pull, can mean it is failing.

Does the SLK automatic gearbox need servicing?

Yes. Specialists recommend an oil and filter change at around 35,000 to 36,000 miles. Check also for leaking cooler pipes and oil at the wiring connector.

Is a Mercedes SLK R170 a good first classic?

It can be: comfortable, practical with the roof up and well supported by specialists. Buy on body condition and a working roof rather than mileage.

Why is the boot of my SLK wet?

Blocked drain holes and tired seals are the usual causes, and the water can damage the central locking pump.

Sources

Checked 20 October 2026.

An independent guide. Not a valuation and not financial advice. Always inspect a car in person or have it inspected before you buy.