Magazine Cover - Classic Cars For Sale - 1000s of Classic Car Reviews, How To Service & Maintenance Guides

Mercedes-Benz R129 SL

Mercedes-Benz R129 SL Published: 12th Apr 2017 - 0 Comments - Be the first, contribute now!

Mercedes-Benz R129 SL

Fast Facts

  • Best model: SL500
  • Worst model: SL600
  • Budget buy: 300SL
  • OK for unleaded?: All
  • Will it fit in the garage? (mm): L 4522 x W 1828mm
  • Spares situation: Excellent
  • DIY ease?: Limited
  • Club support: Excellent
  • Appreciating asset?: Values starting to soar
  • Good buy or good-bye?: Super buy if bought right
Magazine Subscription
The latest issue of Classic Cars For Sale is on sale now - Pick up your copy from all good newsagents including WHSmith or click here to subscribe now

Subscribe to Classic Motoring Magazine and save over 20%

Subscribe NOW

Available at all good newsagents including WHSmith

Fast rising star in the SL family tree that is still great value for money. Essentially a tourer but a polished performer all the same. Typical Mercedes specialist and club support but beware of the so called bargain buys out there which aren’t

Mercedes launched the much awaited replacement for the 20 year old R107 the thick end of 30 years ago after spending a decade perfecting its all new SL, the R129. Compared to its predecessor, the ‘Dallas’ (so dubbed because it featured heavily in the TV series thanks to mega weathly Ewings) the ‘R129’ SL was a revelation; a technological tour de force that immediately moved Mercedes’ game light years forward compared to its rivals and yet these versions trail its illustrious SL predecessors by miles, meaning you can buy one of the greatest cars ever for less than MG Midget money. But should you?


1989 R129 begins full production (original build started a year earlier) as the 500SL, 300SL and 300SL-24 (24v). The new SL was, literally, virtually all new, and based upon the E Class saloon at the time (and one of the German’s best ever efforts we might add), albeit truncated for sports car use. Typically Mercedes, there was the huge choice of engines – from a sweet 2.8-litre six, through to the mid range 24 valve 3-litre 300SL-24, right up to the full strength 5-litre V8 with 326bhp.

1992 Flagship V12 6-litre 600SL joins range offering 394bhp and a mighty 420lbft of torque. There was even a tuned SL60 which managed nearly 400bhp from 6-litres of AMG-tuned V8.

1994 Model names changed by reversing symbols; i.e. 500SL becomes the SL500. New (231bhp) 320 replaces 300-24. Also this year, Mercedes offered special SL models, such as the Mille Miglia edition cars of 1994. The new model proved so appealing, it prompted the late Princess Diana to lease a 500SL (in 1991) and she was the first Royal to drive a foreign car.

1995/6 Facelift sees more subtle look with new bumpers and grille treatment while new sound system features.

1997 Nifty Panoramic glass roof for the removable hardtop becomes a worthwhile option as is a Sports option on some SLs.

1998 Another minor facelift, featuring new style door mirrors and colour-coded door handles, complements a change of leather interior trim. There’s a new 224bhp 3.2 V6 engine for the SL320 while bigger 17inch wheels are fitted across the range.

2001 Final fling after 12 year run before this SL is replaced by the (unreliable) R230, marked by the Final Edition and Silver Arrows special editions.

Driving and press comments

Based on a shortened floorpan taken from the W124 (E Class) saloon, the new SL (Sports Lightweight to you) was never going to be anything other but smooth and surefooted. The R107’s rather dated rear diagonal swing axle gave way to a modern multi-link axle which made the R129 a far more sporting proposition than its aged predecessor – no wonder monthly mag Car exclaimed: “At last! An exciting Merc” before, four years later, revising its opinion to “one of the greats.”

Out on the road, whichever engine choice, the SL inspires confidence in any weather conditions, but the driving experience is a little detached for those used to the raw thrills of a similarly priced (when new) Porsche 928 or even an XK8.

For a start, almost all UK spec R129s were delivered with an automatic gearbox, which admittedly suits the character of the car (like all Mercs to be fair) perfectly, but blunts the fun, even if you use manual shifting. Only the smooth if somewhat underpowered – but admittedly fine for gentle cruising – SL280 had a manual option, but few were specified as such.

Whilst a nice SL320 makes a smooth cruising companion and the SL500 the best all rounder if you don’t mind the running costs, the showy V12 600SL seems quite superfluous as it’s not much quicker than a 500, yet feels more unwieldy due to the greater weight. Add in V12 complexity and running costs and it is clear why there are so few about – or wanted, to be frank. Comparing one to the V12 XJ-S (see Classic Choice in this issue-ed) Car magazine implied that the added four cylinders wasn’t worth the cost or complexity and that you’re better off with a SL500 “It’s every bit as good a car”.

Not everyone was so enamoured mind. Testing the World’s first five-speed automatic in the 300SL-24 Autocar reckoned that, while extremely impressive, this SL failed to live up to its high price (£61,390 in 1990) although conceded that its many talents included the car’s chassis, cabin and controls, but added that the 500SL “is in a different class”.

Think of a better packaged S-Class with no roof and you won’t be far adrift and it’s far more accomplished and polished than the earlier and far dearer R107.

The all-automatic folding hood was a masterpiece in mechanical engineering at the time; one press of a button was all it took to stow the triple lined canvas top completely away. No scraped knuckles undoing recalcitrant catches on this sophisticated sportster. It’s an extremely safe one too for its era thanks to the usual electronic aids we take for granted on moderns. Apart from anti-lock brakes and traction control there’s also an automatic clever roll over protection system.

Despite some mouth watering bhp figures and pace with pose to match, the R129 is not a sports car in the purest sense. But as one notable SL expert said to us a few years ago, it’s the SL he’d gladly take out of all of them on a fast run across the continent.

Values and marketplace

In common with the Jaguar XJ-S, R129SLs can be as cheap as chips but you get what you pay for. Yes, you do regularly see them on sale for much less than £5000, but land yourself one without any form of service history and it can cost that much again for relatively minor repairs – such as to the transmissions or hoods. Given their great value for money, it’s best to spend closer to £8000 at a marque or classic specialist offering a warranty as a deal clincher.

Again, like the XJ-S, R129 values have started to creep up quite unnoticed, because at the other end of the scale £15,000 and upwards is now becoming quite common for really nice SLs and almost double this for the very best, low mileage examples. The Silver Arrows and Final Edition cars can command up to 40 grand, easily outstripping R230 values; in part due to the poor reputation the R129’s replacement has, sadly quickly gained…

Pimped-up cars with their massive non-standard wheels and chrome accessories usually spell trouble and are harder to sell on say SL experts, many who will not touch them or at least will put them back to standard before retailing.

Originality rules where R129s are concerned (and every SL model to be fair) and this will strengthen as they become more popular as classic propositions.

It’s doubtful R129 values will ever match the earlier R107 although prices are fast firming up as enthusiasts turn to this cheaper and arguably better buy.


“Handling is brilliant. Roadholding and brake ditto,” hailed one road test. So tune and titivate at your peril warn major SL specialists because the design was so well developed and executed, meaning any personalising will probably deface values and desirability. No doubt that a sports induction kit, and perhaps suitable engine ECU reprogramming, works to a degree and quality uprated dampers will tighten handling, but you won’t improve much on the standard settings, although if you intend to upgrade look to Mercedes approved AMG hardware.

As with any high performance prestige car, the best ‘improvement’ lies in a full service and sort out (suspension geometry, new quality tyres, and so on) by a marque expert because you can bet your life that many cars have lacked such TLC for years.

What To Look For


  • As with all prestige cars, a service history is critical – certainly you want to see the service booklet stamped by main dealers or specialists rather than normal garages.
  • Watch for insurance costs on the rarer models such as the V12s and the AMG SL60 as these will be at the top of the scale. Conversely, the 320s and 500s can now be insured under some classic car policies with limited mileage and agreed value at surprisingly reasonable rates.
  • If the car you’re looking at does not have a hard top, you will have to find one that fits. The roofs for all R129s are not entirely interchangeable. Late model SLs have a much larger seal around the A-pillars and windshield surround.
  • On pre ’95 cars the wiring loom is known to bio-degrade and new ones cost £1300. There’s lots of electronic wizardry so check that everything works, especially the electric hood that has a host of modules and relays which can malfunction and sorting them out is an expert job.
  • The interiors scrub up well unless neglected but watch for wearing seat bolsters, door panels and kick plates plus broken switchgear and tired trim. See that both sets of keys are there - genuine Mercedes ones are best.

Body & chassis

  • Rust may be an issue – after all, the earlier SLs are almost 30 years old plus were contemporary at the time the famous build quality was starting to slip a bit, although bad cases are extremely rare and usually the result of poor past accident repairs more than anything else.
  • The bulkhead ventilation plenum chamber can rust out causing major water leaks to the front foot well area. Unfortunately, the cure requires extensive stripping out of the dash and heater matrix, de-rusting, making suitable sections of new metal and welding these in position followed by sealing and rust proofing. If there’s water in the footwell, walk away and simply find another, and better SL.
  • Cosmetically, the R129 SL suffers from typical crusty Mercedes metal, wheel arches, front valance (where there’s box section that’s particularly vulnerable) and so on but is nothing too much to fret over generally speaking. n Ensure the hardtop is with the car, because all R129s were sold with one. At the same time, inspect it for dents, as these usually spend a lot of time in the corner of garages during summer months.
  • If the hard top is on, make sure it is taken off and the hood inspected for correct operation and lack of tears or damage. Hoods are triple lined, fully automatic and very costly to replace properly – like the thick end of £5000!


  • Oil leaks are a major problem on V12 cars, particularly the front cover. After a while if left unattended it will soak the right side of the engine ruining the alternator and any coolant or air hoses in the vicinity. The intake manifold will need to be removed to get to the valve cover gaskets to remove the front cylinder head cover. Updated intake gasket spacers will be needed along with the rubber air or crankcase vent hose and all vacuum hoses.
  • If you really must go for a V12, get it professionally inspected as the cost of putting even small mechanical woes in order could end up costing more than the car. If in doubt, walk away.
  • Fresh, high quality coolant is essential on all models to avoid premature corrosion and failure of aluminium and composite parts throughout engine, cooling and heating system. Separate electric pump which feeds heater core is an extra failure point so check.
  • The (M119) engine that powers the V8 500SL is the sturdiest of the lot and is generally fine so long as the timing chains are kept well serviced. The straight six engine (of which the 24V unit is recommend more for its speed than smoothness over the earlier power plant) suffers from the typical weeping head gasket.

Running gear

  • Biggest concern is the special Adaptive Damping System on the rear suspension which features hydraulics and though usually okay, is very expensive and technical to repair. If the handling feels wayward, it points to problems here; has the dash warning lights been tampered with?
  • The rest of the suspension simply suffers form age and hard use so check ball joints and steering links including damper for the steering box. Front springs have been known to break, too.
  • So long as genuine Mercedes parts (or known quality substitutes) have been used, the brakes present no real problems. Rusting and sticking callipers are likely to be due to ‘car wash’ syndrome where the car isn’t used much and water lays on the workings.
  • Are the wheels okay? Cheap replicas are not as good as original Mercedes ones and will look it; check for proper Mercedes stampings and see that the tyres are evenly worn and of the quality and performance the SL demands; pinching here points to slipshod servicing elsewhere.

Three Of A Kind

Porsche 928
Porsche 928
A direct competitor on price when new, but a million miles from the SL driving-wise. A lot harder-edged, with a very stiff ride, but the 5-litre V8 is more powerful than the Merc’s – and of course it’s sportshatch only. Right now the 928 represents outstanding value and there are some incredibly cheap ones out there although repairs may outweigh their real world value. Cracking GTS packs 340bhp from 5.4-litres and is usually manual.
BMW 840/850I
BMW 840/850I
Another hardtop-only option, but despite that, the lovely 5-litre V12 engine endows this coupé with massive performance in a very focused package, yet complete with docility when required. Rust is always an issue on these cars, sadly, and many have been thrashed or tarted up. A shame, as they can be magnificent value plus there’s an easier going V8 (840) model. Both are stuffed full of electronics which can be extremely expensive to rectify.
Jaguar XK8
Jaguar XK8
Probably the closest in character to the SL, the XK just oozes charm and sophistication, plus of course, the same open air experience if you go for the convertible. After the XJ-S, Jaguar cottoned on how to make them so they would last, so reliability isn’t too bad, either but there are some very tatty – as well as tarty – examples out there. Supercharged XKR is heroically fast and XK8 values have never looked so tempting. But for how much longer?


Whether or not the R129 will attain the same classic status as Pagodas and R107s, time will only tell. But there’s no argument that it’s the best all round SL and a darn sight more durable than the model that replaced it! Prices are rising and while there’s still plenty of good value, yet sound enough cars around, it won’t stay this way for much longer.

Share This Article

Share with Facebook Share with Facebook

Share with Twitter Tweet this article

Share bookmark with Delicious Share bookmark with Delicious

Share with Digg Digg this article

Share with Email Share by email

User Comments

This review has 0 comments - Be the first!

Leave a comment

Keep it polite and on topic. Your email address will not be published. Please do not advertise products, all posts of this nature will be removed. We do not stock or supply any of these products, we independently review these products.

Subscribe Today
Latest Issue Cover - Click here to subscribe

Subscribe to Classic Motoring Magazine and save over 25%

Britians top classic cars bookazine