Mercedes-Benz built its reputation on indomitable engineering prowess during the mid-20th century, so when the 1980s brought a boom in computer technology, it set upon the job of leading the automotive industry in that area as well. One of the best examples from this time in its history is the R129-generation SL roadster. 

Here was a car whose superbly proportioned but ultimately simple exterior belied the sheer complexity and advanced technology within. The convertible roof was the first ever fully-automated electro-hydraulic system which clipped itself into place – and when it was down, a hydraulically restrained pop-up roll hoop (bound in leather, of course) was ready and waiting to deploy in just 0.3 seconds if the car’s sensors detected a roll-over accident happening. 

The R129 also had height-adjustable adaptive dampers, electronic ignition, traction control, a suite of airbags and award-winning, all-electronic, magnesium-framed seats with 20 design patents and an integrated height-adjusting seatbelt system. The SL’s designer, Mercedes icon Bruno Sacco, considers this car’s design to have been “perfect” – a view which is perhaps vindicated by its 12-year production run from 1989 to 2001, during which nearly 205,000 were sold.

Later-year cars are believed to have suffered from a company-wide cost-cutting strategy enacted around the time of the late-‘90s Daimler-Chrysler merger, so this early-year 1991 500 SL, powered by the time-honoured ‘M119’ five-litre V8, should be one of the more desirable non-AMG examples around. 

Of course, high technology and advanced engineering need to be looked after properly over time, but reliable R129s are certainly out there and they remain a heck of a lot of car for the money. Take care of it and it will certainly take care of you.

Those special front seats strike a balance between sporty and supportive as they welcome you into a cabin that has aged remarkably well over the past 30 years. The black leather shows only superficial wrinkles on each seat and the surrounding carpets look all but new, while the wooden dashboard trim also presents very well. The steering wheel shows wear but not tear, as the rim’s leather is smoothed-down but otherwise perfectly intact.

One point of note for the buyer is that the headlining is peeling off at the edges on both the hardtop and (less so) the convertible hood, revealing the sound-deadening foam behind. The area directly over occupants’ heads is still properly attached, so it doesn’t touch one’s head, but it would benefit from being neatened up.

The bodywork and colour-contrast plastic cladding present very well indeed with very few marks to show in the paintwork at all – save for the detachable hardtop showing two small areas of bubbling, one at the base of each rear pillar next to the glass window. The popular Alamak wheels have also survived exceedingly well, with just the smallest marks on the outermost part of two rims to show for over 30 years on the road. Finally, there is a stone chip in the passenger-side headlight lens and some small discolouration on the whitish inner bezel in both headlight units.

These minor imperfections aside, you will find this is a complete and original exterior that sets an excellent overall first impression of both the car and its driver.

Pull the plastic organ stop hiding within the three-pointed star and lift the padded bonnet to reveal an engine bay in excellent original condition. The M119 engine, whose design had by this time proven itself in the Le Mans-winning Sauber C9, produces 322bhp and 332lb/ft of torque in 500SL specification, giving this beefy roadster the straight-line clout of a contemporary sports car and a suitably brawny soundtrack.

After an initial issue with the immobiliser on the day of our photoshoot, the SL was eventually persuaded to start and then settled into a smooth, consistent idle without any further hiccups. The hydraulic nose lift switch next to the headlight controls, however, did not do anything. 

Service invoices show that in January 2018 specialist garage SS Motors in Surrey fitted new front and rear gas spheres as well as two front shock absorbers, as part of a thorough troubleshooting and refreshing process detailed across four pages (see paperwork photos) and costing over £6000. The suspension then received further attention in March 2019, so the unresponsive switch is unlikely to be a mechanical problem.

Inside, the seller reports that the instrument cluster was replaced with a used one when the car had done 70,512 miles. Because the new cluster’s odometer showed 85,719 miles at the time and was not reset, the car’s mileage is claimed to actually be 15,207 lower than shown. The MOT certificates meanwhile have quoted the mileage indicated on the odometer verbatim.

This generation of SL was a truly groundbreaking car when new but has remained largely under the classic car market’s radar for a long time. 

This surely won’t be so forever, especially as values of other SLs continue to rise and people start sniffing around R129s looking for, dare we say it, ‘the next big thing’. This car has one or two points for a specialist to look at, but given the maintenance that has already been done and condition it’s in now, we are most likely talking about minor fixes here – some new headlining and a dashboard switch. As long as you understand the running costs of this flagship Mercedes-Benz and go in prepared, then it won’t bite. It will just have you cruising along in something that feels ten times its current value.