With a 60+ year continuous history, Mercedes-Benz’s range of SLs is rightfully part of our automotive lexicon, thanks to its reputation for built-to-a-standard rather than built-to-a-price quality and upmarket image. But while most models benefitted from quiet evolution, the 1989-launched R129 was an undoubted step change in open-top automotive engineering.

As one of the cornerstones of the international automotive show scene, the Geneva International Motor Show has presented some serious showstoppers during the annual March fixture. Jaguar’s E-Type (a car admired by Enzo Ferrari) back in 1961 and Marcello Gandini’s sensational prototype for the Lamborghini Countach ten years on are two standouts that spring to mind, but there have been plenty of others in more recent years – such as Mercedes- Benz’s R129 SL, which was debuted back in 1989.

With an understated but stylish body clothing a raft of clever technology – including the famous ‘pop-up’ roll bar which made the stated 250km/h performance safe to explore – the Bruno Sacco-styled SL was a break in every respect from the outgoing SL, codenamed R107. In fact, it was so different that show-goers unfamiliar with the three-pointed star’s SL history could’ve been forgiven for asking if there was perhaps a model in between…

Such an observation might have amused at the time but the reality was that the R129 was an overdue model in every sense, thanks to the R107 having been in production for 19 years – an unthinkable time frame in the modern era but understandable in the late 1970s when open-top cars were under threat from US safety legislation. As a result, Mercedes was reluctant to invest in a new model and elected to evolve its already type-approved popular SL with engine upgrades and detailed styling tweaks. But by 1984 the writing was on the wall for the pretty, chrome-laden sports car (which still featured trailing arm rear suspension) and the engineers in Stuttgart took the plunge for an all-new model based on a shortened version of the new W124 E-Class platform.

Ever mindful of the marque’s reputation for automotive safety (it had pioneered the use of crumple zones) the R129’s engineers added a raft of driver safety aids including optional ASR (anti-skid control) and ADS, an active damping system. The former used computer technology to assess throttle inputs and, if necessary, limit them by backing off and momentarily braking the affected wheel. The ADS, on the other hand, controlled the damping rates in response to driving conditions, applying one of four settings between soft and hard while on the move and reducing the SL’s ride height by 15mm as soon as its speed exceeded 120km/h to improve stability and reduce drag.

Both aids may be widely adopted in today’s luxury cars, but they were leading edge 28 years ago – much like the ‘pop-up’ roll bar which could be raised on demand or relied upon to automatically shoot up (in a ⅓ of a second) if the roll bar’s control module sensed that the car was in danger of turning over.

Also new for the SL range was an electro-hydraulically operated soft top that could be raised from behind a set of neat, folding body-coloured panels at the flick of a button (while entertaining onlookers). Or drivers could opt to fit the standard aluminium hardtop (as with previous SL models) that transformed the open-top sportster into a snug-feeling luxury GT.

Inside there were plenty of new gadgets, including climate control and ten-way, electrically adjustable seats that featured clever ergonomic thinking in their operation, which was by seat-shaped buttons as well as memory settings. Another first was the new SL’s built-into-the-seat inertia-reel seatbelts, which were automatically height adjustable with the headrest. There was also a driver’s side airbag and an electrically adjustable steering wheel, while ABS and cruise control were familiar fitments for owners of late model R107s.

But most importantly, the W124 platform that lay underneath provided up-to-date, five-arm multilink rear suspension, configured to provide anti-lift, anti-squat geometry – all much needed for one of the R129’s most impressive features (in range-topping 500SL form): its 32-valve, 5-litre V8. This unit was good for a mighty 245kW and 460Nm! Those numbers were seriously punchy for the late 1980s when Porsche’s autobahn-storming 928 S4 boasted 10kW less and BMW’s mighty V12-engined 850i was celebrated for its 220kW metric.

Known internally as the M119 engine, the all-alloy unit’s impressive output came thanks to its twin-cam design which featured variable valve timing on the intake side. It was a serious piece of engineering that outstripped the marque’s already potent 5.6-litre V8 and would also feature in the luxury German carmaker’s famous 500E saloon, as well as its S-Class series. And, in heavily adapted, twin-turbo guise, it powered the brand’s famous Sauber C9 to victory at Le Mans in 1989.

As with previous SL releases, there was an ‘entry-level’ option in the form of the 3-litre straight-six – the 300SL – which came in two guises: standard 12-valve with 140kW or a 24-valve that was good for an additional 30kW. These were available in four-speed automatic or five-speed manual form, unlike the 500 which was auto only.

Well-heeled South African customers only got the option of the full-fat 500SL version initially and CAR magazine tested one as early as May 1990, when it was listed at a whopping R525 000. That was around R180 000 more than a Carrera 2 and R220k over the marque’s own already impressive 560SEC! Price point aside, CAR’s testers were understandably quite taken with all the new technology and the SL’s impressive performance, notably its 0-100km/h in 7.1 seconds and 250km/h (limited) ability, together with its perfectly balanced chassis.

Less than two years on, that performance was given a boost when Mercedes-Benz launched the 600SL, powered by a 290kW, multivalve 6-litre V12 – also known as the M120 engine which, in enlarged form, was used in the Pagani Zonda and various AMG products.

In late 1993, Mercedes switched its nomenclature around and the 500SL became the SL500 while the 300SL made way for the SL280 and SL320, both in multivalve-only form. Three years on various styling tweaks followed, while the V8 and V12 models gained a five-speed automatic box and side airbags. And in late 1998 the R129 underwent an engine swap, with the SL280 and SL320 now featuring V6 units and the SL500 a less powerful, three-valves-per-cylinder V8. There were more external tweaks, including a switch to 17-inch wheels, but by and large those changes saw the SL through until 2001 when the R129 gave way to the R230 class (the first SL with a retractable steel roof), by which time more than 200 000 examples had rolled off the production line.

Fast-forward 20 years and the R129 still makes a mark, both in terms of styling and metrics on the tarmac, as these two examples owned by collector Arno Taljaard attest: an early (1992) 500SL in Pearl over Ice Blue and a 1997 SL320 in Ruby Red. The pair are part of a wider collection, which includes two R107s (a rare manual 280SL and a 350SL), and seeing them highlights just how radical the R129 was when it was in the limelight at Geneva nearly three decades ago. The two-tone body panelling is striking, particularly on the early 500 with its distinctive orange indicator lenses, and the smooth styling is typical of the restrained shapes ushered in by the marque in the 1990s.

Getting behind the wheel of either is a reminder of another step change over the outgoing model: interior space is vastly better, even though the electrically adjustable seats are chunky affairs, and the dashboard infinitely more ergonomic in its layout, with an array of gauges and warning lights in full view. There’s a quality feel to the experience, even all these years later, with doors that close with a solid thunk and switchgear that still feels robust. That perception continues on the move; the body has that hewn-from-granite feel to it, without a trace of scuttle shake over bumpy surfaces.

And when on the move in the earlier car you soon become aware of the 5-litre V8’s sheer urge – although the length of travel on the organ-like accelerator pedal, which is typical ’80s Merc, can make the SL feel a tad lethargic on pull-away. No surprise as this sportster weighs in at close on 1.8 tonnes, thanks to all the componentry. But, be generous with your right foot and the effortless 460Nm of torque comes on stream very quickly, particularly in ‘Standard’ rather than ‘Economy’ mode, when the four-speed box will skip first gear and change up quickly.

That’s another feature, common to other Mercedes products of the time as a nod to saving fuel but given the car’s price tag at the time that probably wasn’t a priority, and certainly selecting ‘S’ makes the big V8 feel decidedly punchier: let the rev counter run towards the red line and it rewards with serious grunt that won’t embarrass you if you’re sharing the tarmac with more modern performance machinery. And when the going gets twisty the SL remains composed, with the combination of ADS and the wide (225R16) rubber keeping the car stable.

A switch to the 500’s smaller-engined younger brother doesn’t disappoint, mind, despite the drop in power; the extra ratio in the five-speed automatic gearbox keeps the engine in the torque band as you work your way up the ratios. The engine needs more revs before it rewards with pace, but it’s no bother as the multivalve engine is happy to spool up easily on demand. What the SL320 lacks in outright urge it makes up for in refinement from the inline ‘six’ engine. While the earlier 500 is the R129 SL that made the headlines back in Geneva, the later car offers all the quality and enough of the performance to be worthy of the SL name.

With values for earlier SL derivatives rocketing in recent years the R129 is arguably the next one on the rise, and the model’s long production run and variation in models means there’s a sizeable range of values. As a proper modern classic, any good variant offers a lot of innovative technology for fans of the three-pointed star. Fans who, like me, could only ogle at the technical wizardry and price list that made headlines when the covers came off the R129 at Geneva all those years ago.