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Mercedes R129 SL

Sports Star Published: 14th Jul 2011 - 0 Comments - Be the first, contribute now!

Mercedes 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 1828
  • Spares situation: Excellent
  • DIY ease?: Limited
  • Club support: Excellent
  • Appreciating asset?: The next big thing. Buy now!
  • Good buy or good-bye?: Great buy if bought right
Prestige badge for Mondeo money if you buy well Prestige badge for Mondeo money if you buy well
Engines span from straight six to V12; tough, durable Engines span from straight six to V12; tough, durable
Electronics galore, idiot lights may be bypassed Electronics galore, idiot lights may be bypassed
Interiors stand up well, most are auto and two-seater Interiors stand up well, most are auto and two-seater
Body rot uncommon, scrapes and dings much less so Body rot uncommon, scrapes and dings much less so
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Speed, style, sophistication – the R129 SL Mercedes has it all to spare yet remains superb value for money!

Pros & Cons

Sheer style, comfort and convenience with terrifi c build quality and an open top
V8s and V12s are massively thirsty and expensive to repair. Lots of dogs about
£3000 - £14,000

Since the 1950s, the SL has been the pinnacle of Mercedes’ sports range, starting with the iconic 300SL with its futuristic gullwing doors and swooping lines – at a time when a Morris Oxford was what volume producers were foisting on us. But in those 50 years the world has changed immeasurably, with every new incarnation of the SL introducing more power and luxury to satisfy those well-heeled buyers. The ‘Pagoda’ SL years from 1963 to 1971 were testimony to this, but the longest running SL was the R107 model, introduced in 1971 with a an SL fi rst – a V8; this ran largely unchanged in the styling department until 1989 when its much-anticipated replacement fi nally broke cover.
Compared to its predecessor, the ‘R129’ model was a revelation; a technological tour de force that immediately moved Mercedes’ game forward light years and yet these SL remain in the shadows if its illustrious predecessors. Not for much longer though! According to Mercedes specialists the ‘Dallas’ (remember that soap) SL is going to be the next Big Thing – so buy now while prices remain JR’s loose change!


SL is built like a merc used to be. And should be!

The old R107 had a long and proud service life so the R129 was, as expected, 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 the 24 valve 3-litre 300SL-24, right up to the full strength 5 litre V8 with 326bhp, itself trumped by a 6-litre V12 pumping out a massive 409bhp. There was even an SL60 which managed nearly 400bhp from 6-litres of AMG-tuned V8. The icing on the cake, though, was the bank vault build quality which, as it turned out, was the very best Mercedes has managed before or since. Confusingly, Mercedes did mess around with the model designations; 1994 cars were the fi rst to have the new designation. For example, the 500 SL now became SL 500. Also starting in 1994, Mercedes offered special SL models from time to time, such as the Mille Miglia edition cars of 1994 or the Silver Arrows of 2001. The newmodel proved so appealing, it prompted Princess Diana to lease a 500SL in 1991 – the fi rst Royal to drive a foreign car; but let’s face it, if you’re going to court controversy, a 326bhp sports car makes it worth it!


Based on a shortened fl oorpan taken from the W124 (E Class) saloon, the new SL 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 better sporting proposition than its predecessor – no wonder monthlymag Car exclaimed: “At last! An exciting Merc.”Out on the road, whichever engine choice, the SL inspires confi dence 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. 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 SL280 had a manual option, but very few were specifi ed as such. Whilst a nice SL320 makes a smooth cruising companion and the SL500 a more urgent proposition, the V12 600SL seems quite superfl uous 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. No, the SL is best sampled at a brisk, but not breakneck pace and it all suddenly makes sense. Think of a better packaged S-Class with no roof and you won’t be far adrift. Journey times have a habit of seriously shrinking, particularly in V8 and V12 SLs – as will your bank balance when you check the 18mpg fuel consumption! 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 canvass top completely away. No scraped knuckles undoing recalcitrant catches on this sophisticated sportster. It’s a safe one too thanks to the usual electronic aids we take for granted on moderns. Apart from anti-lock brakes and traction control there’s also a automatic clever roll over protection system. Finally, it built like you’d expect a Mercedes- Benz to be made.


With a model spanning 12 years, the earliest of which is now over 20 years old, the R129 can be seriously cheap. Just £3000 will get you into a leggy 1990 300SL, but it’s not to be recommended; any decent SL will start at £5000 and upwards, with both the six and eight cylinder models similarly priced at this age due to the higher running costs of the V8s, which peak at around 12k for a top, low mileage post-2000 car.

What To Look For

  • Avoid ‘pimped-up’ cars with big non-Merc wheels and chrome accessories. These almost always spell impending trouble – and won’t be easy to sell on, either. Originality rules where Sls are concerned and this will strengthen as they become more popular classic propositions.
  • 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.
  • Rust is not a major issue on this model and rightly so… If there is any in evidence, it may well have been poorly repaired following accident damage. Check carefully for this and also look for rust at the bottom rear sides of the hard top. Do not tolerate anything less than perfect bodywork, as the cost of restoration is uneconomic at this time.
  • Make sure 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. If the car you’re looking at does not have a hard top, you will have to fi nd one that fi ts. The roofs for all R129s are not entirely interchangeable. Late model SLs have a much larger seal around the A-pillars and windshield surround.
  • 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 – think the thick end of £5000!
  • 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 proofi ng. If there’s water in the footwell, walk away and fi nd another SL.
  • If the car is model year 1993, 1994, or 1995 more than likely there was or will be a wiring harness issue. It’s a known problem but a recall was never issued. Repairing this can cost several thousand pounds. If you are considering a 1993 - 1995 model year and can’t verify if the harness was replaced, take the car to a good Mercedes-Benz specialist.
  • Engine 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 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.
  • 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.

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 850i
BMW 850i
Another hardtop-only option, but despite that, the 5 litre V12 engine endows massive performance in a very focused package, yet complete docility when required. Rust is always an issue on these and many have been thrashed or tarted up. A shame as they can be magnifi cent 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 thereare some very tatty – as well as tarty – examples out there. Supercharged XKR is heroically fast and XK8 values have never looked so tempting.


If you’re in the market for a sporting drop-top without all the trials and tribulations of lesser convertibles, then the SL is for you. Fantastic spares availability, even from main dealers, and plenty of specialists make this a classic in the making that you can buy with your head as well as your heart. As long as you take your time and buy the best condition you can afford, your SL should repay you with a great ownership experience at very reasonable lifetime cost. The main dilemma will be which engine to go for, but whichever one you settle on, it’s clear the R129 will never be cheaper!

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