Mercedes-Benz SL73 AMG: excess express

By Aaron McKay

| 25 Aug 2026

Classic & Sports Car – Mercedes-Benz SL73 AMG: excess express

It is possible that Mercedes-Benz acquired AMG to subdue this once independent tuning company’s wildest whims of the 1980s, to keep boxed wheelarches from returning on another S-Class coupé or to curtail the gauche, colour-coded grilles.

But it’s more likely that Stuttgart’s pragmatists saw the near-limitless margins to be made from a growing set of customers who wanted more. Much more.

At the opposite end of the spectrum from a 190E minus a radio or electric windows and wearing the austere pride of everlasting quality, there was profit through personalisation that would change the course of Mercedes products for decades to come.

This Mercedes-Benz SL73 AMG’s sumptuous cabin, with stitched hide and glossy veneer by the marque’s Designo programme

Stuttgart described its new arrangement with AMG in late 1990 as an ‘intensive co-operation’ in the development, production, sales and servicing of both cars and related parts; it would also take on the preparation of its DTM and GT Championship works entries.

Dealers had stocked parts from the Affalterbach tuner in the past, but now fully kitted-out AMG demonstrators would appear, just as they were also preparing for a raft of new Mercedes-Benz models.

The leading edge of both was the R129 SL, a technical tour de force building on the established reign of its open-topped, do-it-all sports car predecessor.

The SL73 AMG’s clear and simple dials

While praise was showered upon the 300SL, 500SL and the V12-powered 600SL flagship, along came an AMG version, the 500SL 6.0.

With 100mm bores taking the standard 5-litre V8 to 5956cc, 385bhp and 417lb ft, it even outpaced the 600SL over the standing quarter-mile and standing kilometre – and especially off the line, given that it was some 200kg lighter than the V12 car.

Introduced in 1991, it was one of the first AMG cars to have been displayed in full form in Mercedes-Benz showrooms, and it formalised to the outside world the extended relationship between the two firms.

The pricey and exclusive Mercedes-Benz SL73 AMG was the preserve of the elite

These new-generation AMG products were more consciously suggested as packages, equipped with the bodykits, split-rim alloy wheels, sports suspension and engine modifications that were all, technically, specified separately on the order sheet.

Apart from the famous but scarce 300E ‘Hammer’, past examples of fully ported and polished heads on bored-out motors with custom AMG exhaust systems were relatively rare, even on the ultimate W126 S-Class and R107 SLs.

Most had only a mixture of cosmetic and chassis options, but now the idea of an AMG model was being formed.

AMG bored and stroked the Mercedes-Benz SL600’s V12 to give the SL73 7291cc and 525bhp

Ironically, this was helped in part by the concurrent development of the Mercedes Designo programme, a bespoke trim and paint offering launched in 1993.

Advertising 3000 combinations, most of them garishly period, the order system was brought in alongside AMG models in the more exclusive areas of selected showrooms.

Hot on the heels of the first full Mercedes-AMG joint project, the C-Class-based C36 AMG of 1993, the 1994 SL60 furthered this thinking as a model in itself, rather than a 500SL with a 6-litre V8 plus accessories.

The Mercedes SL73 AMG’s lowered suspension retains the self-levelling hydropneumatic struts used by the SL600

You could still order one of these rocketships to look like a pedestrian 300SL, but it’s doubtful that anyone ever did; certainly, more were inspired to do it the other way around – to see how much of the AMG catalogue they could afford, in an attempt to disguise their cars.

An AMG exhaust for DM2050 might have felt like a more pragmatic option against the DM29,800 needed to convert a 500SL into the SL60.

But by the time it was replaced by an SL55 in 1998, 633 people had decided the full-fat car was worth the outlay.

This rising sales success was welcomed by the greater powers at Mercedes, as it navigated the aftershocks of a tepid early ’90s economy and an existential shift in philosophy that steered it into a merger with Chrysler in 1999.

This Mercedes-Benz SL73 AMG comes with a removable hardtop

A strong demand for high-value AMG versions would help with profits in the US, where the weak dollar was threatening the prospects of a huge product range that prioritised volume.

As a new boom period rode on the financial rewards of globalisation, property markets and the internet, AMG was then poised to serve as the de facto flagship for a modernised Mercedes looking to shake off its conservative image.

Jürgen Schrempp, chairman of Mercedes-Benz from 1995 to 2005, was in tune with this growing appetite for performance-led range-toppers.

The Mercedes-Benz SL73 AMG has ‘V12’ badging, in case you were in any doubt

He saw further opportunities to capitalise on the marque’s motorsport involvement, which then spanned DTM, Formula One, IndyCar and the GT Championship.

AMG didn’t have a hand in the open-wheelers, but F1 circuits suddenly featured a rash of safety cars sporting the three-pointed star and Affalterbach tuning.

With hope on the horizon for a temporarily troubled Mercedes-Benz, and as AMG versions of everything started appearing – even for the new A-Class hatch and ML SUV – why not introduce an even higher echelon of ultimate SL?

The ministrations of AMG turned the R129 Mercedes-Benz into the fire-breathing SL73

Although 25 of the 35 518bhp SL72 AMGs built from 1995 went to the Sultan of Brunei, there was enough wider interest to reintroduce a V12-powered super-SL, the 489bhp SL70, the following year – and 120 of them were made.

Then, in 1999, what is today considered to be the peak of this escalating madness was introduced: the 525bhp, 553lb ft SL73 AMG.

By that time, AMG was becoming a serious operation.

Having established a third plant in 1990, and with a total workforce of 400, in 1999 it was fully incorporated into Mercedes-Benz and the road-car facilities were modernised with a new, devoted engine department and test rigs, while the motorsport section was re-established on its own.

The Mercedes-Benz SL73 AMG usually kept the SL600’s 2.65:1 final-drive ratio

As annual Mercedes-Benz production passed a million vehicles for the first time, this once small tuning house grew alongside it and into the mainstream lexicon as it raised the horsepower and subtly aggressive styling to pose a serious threat to BMW’s M division.

A proliferation of Benz-based rivals, in the form of the Brabus 6.0-32, Carlsson C60 and even a provocative RennTech SL74, remained niche options on the sidelines.

Yet the SL73 was never really in the common realm.

Aside from the prohibitive price, some 50% more than that of a standard SL600, its ‘ultimate’ status in the rising AMG pantheon meant most of the 43 built, along with its S73 and CL73 siblings, were fated to live sheltered in collections.

The Mercedes-Benz SL73’s headlight controls

‘Our’ car has spent most of its life hidden in Switzerland, having been bought new by Benji Rothschild as a mere paragraph in his family’s history of acquiring extraordinary vehicles.

Finished in Azurite Blue, a standard factory colour, and with the restrained bodykit of a Mercedes-chastened AMG for the 1990s, it looks at first rather unassuming.

Only the 18in wheels – 8.5in wide at the front and 10in at the rear, and sunk into factory-rolled arches on suspension that sits 25mm lower – hint at the menace beneath the surface.

This Mercedes-Benz SL73 AMG’s patinated carbonfibre confirms its capacity

The mighty V12, up to 7291cc thanks to a 1.5mm-larger bore and 12.2mm-longer stroke than the SL600, and with a slightly higher compression ratio of 10.5:1, reveals little of its internal exotica from a cursory look.

Its carbonfibre dress between the aluminium intakes and over the individual coil packs is the only clue, labelled with ‘7.3’ at the front.

Small cracks from years of heat cycles are worn with a collector’s pride, confirming the originality of something that can relatively easily be replicated – much like adding the AMG wheels, exhaust and badges to a regular SL.

The SL73 AMG’s 10in-wide rear wheels required rolled arches, also offered as a dealer option for any R129 model

It was this car’s provenance that attracted current owner Raj Sira two years ago.

“It is perhaps the highest-specification SL73 AMG that exists, sold originally for around half a million Swiss francs,” he says.

“The level of detail is incredible: the closer you look, the more you notice that everything is trimmed in leather.

“But it took me 18 months of persuading and negotiating to buy it before a Swiss Ferrari dealer sold it on behalf of the Rothschild family.

“I was on the next plane there and drove it back over the Alps.”

AMG-branded, split-rim alloy wheels are a subtle nod to this classic Mercedes’ exclusivity and performance

For those who follow the movements of these rarefied AMG unicorns, this SL73 caused a sensation when it was displayed at this summer’s London Concours in June 2026.

But at our quarry photoshoot location there is an initial bemusement over the fuss that this relatively modern Mercedes-Benz SL is getting.

The site manager had expected the classic gullwing 300SL, he tells me, as I struggle to explain the significance of the car.

That said, the 7.3-litre figure raises an eyebrow, even with 11-litre construction monsters rolling along nearby.

‘The Mercedes-Benz SL73 AMG was never really in the common realm. Its “ultimate” status meant it was fated to live sheltered in collections’

Only the slightest rasp from the exhaust tips, barely heard from inside the cabin, announces the quick-spin awakening of this supposedly demonic V12.

The turbine-like hum aspirating far ahead of the restful dials is exactly the opposite of what you might expect from legendary tales of a rare AMG SL with the engine from a Pagani Zonda.

A click into ‘D’ and a light twirl of the steering wheel is likewise just as refined as any other Mercedes-Benz built from this era of determined isolation.

But the seemingly eternal thrust found in the accelerator pedal has the force of a hot rod to end all hot rods, launching a wave of torque that splits between the unprepared rear Dunlops and a traction-control system facing catastrophe.

The wild Mercedes-Benz SL73 AMG didn’t appear on the usual order sheet

The V12 breathes with a hollow, slightly gruff rush of symphonic twin ‘sixes’ balancing each other out.

In second gear it begins to dig in, as the revs fly to a soft buzz at the 6000rpm redline; in third the road is drawn underneath like a frantic conveyor belt that accelerates the speedometer needle around the dial at incredible speed.

Brake, turn in and there is the eerie calm of a normal, composed SL serving balanced, somewhat detached handling and a smooth ride made only slightly firmer than usual by larger wheels.

Settle down and you could almost forget it ever happened.

The Mercedes-Benz SL73 AMG’s folding roof stows away neatly

With the road, and any stray rivals, well and truly pummelled into submission, the SL73 glides along with hardly a gentle breeze entering the leather-lined realm of every-box-ticked luxury.

Stitched hide covers the tonneau cover, the door cards – which are neatly punctuated by AMG-branded lock-pins – and even each line of the air vents.

In the glossy burr walnut of the centre stack, there is no allowance for any suggestion of a missing button.

The digital lap-timer and tape deck are now as redundant as the primitive GPS navigation display in the single-DIN head unit, both relics of a time just before Mercedes-Benz was steered into the tech-crazy 21st century.

The Mercedes-Benz SL73 AMG’s centre console is a late-’90s button-fest

The SL73 AMG remained available until 2001, when the R129 was replaced by the lighter, more dramatically styled and cleverly re-roofed R230.

More than just the folding hardtop, there were AMG models built into the product plan, with a supercharged V8 SL55 in 2002 and twin-turbocharged V12 SL65 arriving in 2005 to head up the next generation of Affalterbach monsters.

In 2000, AMG produced some 11,500 cars; by 2005, that figure was more than 20,000 – although what was by then a division of Mercedes-Benz steadfastly retained its independent character, with internal development programmes and its claim of one man to one engine.

The glass panel in the hardtop roof of this SL73 AMG was an option

Its slightly unhinged charisma ran free within the eccentric confines of a marque looking for a modernised identity, creating various Black Series models and the SLS along the way.

Today, AMG is a more dominant part of Mercedes than ever.

This adds a certain mystique to the special-order SL73 AMG, which was never on official price lists even after the 1999 takeover.

It was an extravagance beyond product planning, a super-SL with an engine more appropriate in an Italian hypercar and a price-tag that only makes sense to those for whom money is no object.

Although hidden under the sensibility of a 1990s-era suit, the SL73 belonged to an AMG-branded extreme that had no purpose beyond being the absolute most of all.

Images: Jack Harrison

Thanks to: Springfield Farm Quarry, Beaconsfield; London Concours

Factfile

Mercedes-Benz SL73 AMG

Sold/number built 1999-2001/43
Construction steel monocoque
Engine all-alloy, dohc-per-bank 7291cc V12, electronic fuel injection
Max power 525bhp @ 5500rpm
Max torque 553lb ft @ 4000rpm
Transmission five-speed automatic, RWD
Suspension independent, at front by MacPherson struts rear multi-link axle, telescopic dampers; hydropneumatic spring struts, anti-roll bar f/r
Steering power-assisted recirculating ball
Brakes discs, with servo and ABS
Length 14ft 7in (4470mm)
Width 5ft 11⅓in (1812mm)
Height 4ft 3⅓in (1303mm)
Wheelbase 8ft 3in (2515mm)
Weight 4519lb (2050kg)
0-62mph 4.8 secs
Top speed 155mph (limited)
Mpg 20
Price new CHf500,000 (est)
Price now £300-600,000*