Mercedes-Benz 450SLC 5.0: the world’s least likely rally car?

By Martin Buckley

| 12 Mar 2021

Classic & Sports Car – Mercedes-Benz 450SLC 5.0: the world’s least likely rally car?

The old-car world loves its homologation specials.

Always perceived as the fastest, rarest and sexiest of their particular breed, they were built in short runs as a way of satisfying FIA regulations in a manufacturer’s particular field of sporting endeavour.

If the rules say you have to build 500 or 1000 replicas for public sale, it tends to ensure the works cars don’t emerge as freakish contraptions that bear no resemblance to the ones you can buy in the showroom.

The SLC has a longer wheelbase than the SL, which is clear when seen in profile

The BMW 3.0 CSL is the example that springs most readily to mind; the road cars were (necessarily) watered-down versions of what the factory was racing in Group 2 and, like many such stripped-back road-racers, they were not a very easy sell in period.

But as a long-term ambassador for the BMW image, the CSL was a masterstroke that still pays dividends today.

Yet who can remember the Mercedes-Benz 450SLC 5.0?

Known as the 500SLC for its final two seasons, this too was a lightweight version of a well-established two-door pillarless coupé.

The 450SLC 5.0 has effortless rather than outrageous performance

It was not built to homologate a track star in the CSL mould, however: AMG highlighted the limitations of the model in that arena by only winning one European Touring Car Championship event in its lowered Group 4 SLC in 1980.

No, the true works SLCs were destined to become long-distance endurance rally competitors.

Heavy and luxurious, they were unlikely candidates. Yet, in the right events, these big V8 coupés proved spectacularly effective – at least for a while.

It could be argued the level of resources that Daimler-Benz AG aimed at the SLC project, both in terms of organisational muscle and even drivers’ fees, changed the face of rallying for ever.

Vic Preston Jnr and Mike Doughty head for fourth on the Rally Bandama in Ivory Coast in December 1979

The success of the 280E in the 1977 London-Sydney Marathon had given the firm a (cautious) taste for the positive publicity that could be generated.

But to keep winning against smaller, lighter Fiats and Fords with much better power-to-weight ratios, a more potent car than the W123 was required.

Enter the SLC, a 15½ft four-seater coupé that was not only more rigid than the SL it was partly based on, but also more stable thanks to its longer wheelbase.

To take out some weight – a claimed 125lb – all of the non-stressed opening panels would be in aluminium; later the two-seater SL got an alloy bonnet as part of a product-wide weight-loss programme.

This was the first application of this bigger, lighter V8

Best of all, the SLC 5.0 was the first to get the new all-aluminium version of the M117 V8, opened out to 5025cc (4990cc for tax purposes) and 20bhp stronger (at 240bhp) and 88lb lighter than the iron-block 450.

This was seen as an ideal way of collecting data on the new engine technology, where the iron cylinder liners had been eliminated and the exhaust port area increased by 11% thanks to larger, sodium-filled valves.

With different internal architecture, this aluminium V8 would be the mainstay of the W126 S-Class saloons from ’79 onwards.

Running a 12.5% higher rear axle ratio, the 450SLC 5.0s as sold to the public – internally designated W1070.26 – were good for 140mph.

The Mikkola/Hertz SLC splashing on during the 1979 Rally Bandama

Fundamentally, the 14 cars used by Mercedes’ competition department for testing, training and events were surprisingly faithful to the showroom specification.

They recognised that the standard Type 722 three-speed automatic gearbox was the strongest option, and the works cars even kept the power-assisted steering.

The 450SLC 5.0 would go on to be the first V8-engined car (and the first automatic) to win a World Rally Championship event in a career that was short but impressive.

In tests of strength and endurance, driven by the likes of Andrew Cowan, Björn Waldegård and Hannu Mikkola, the SLCs put in some epic performances.

Hannu Mikkola and Arne Hertz en route to victory on the 1979 Bandama Rally in Ivory Coast

On the gruelling 39-day, 30,000km Vuelta a La América del Sud held in September 1978, SLCs – still standard 450s at that stage – took the top five places in their debut event.

Winning driver Timo Mäkinen’s copilot was a certain Jean Todt, later to be the Ferrari F1 team manager and FIA supremo.

It was much the same story on the 3500-mile 1979 Ivory Coast Rally, although Mercedes’ success – a clean sweep of the top four positions – has to be set in the context of the unheard-of resources the Germans threw at the event: 500 spare tyres and 35 support vehicles, including planes and even helicopters.

The SLC team took the top four spots on the 11th Ivory Coast Rally in ’79

Later, when Cowan lost his rear brakes on an event in New Zealand, the team helicopter came into its own by flying in a complete suspension assembly that was bolted on in 20 minutes.

But not even Stuttgart’s fat wallet, nor the organisational skills of legendary engineer Erich Waxenberger, could help the SLCs on the shorter European rallies in 1980.

Jonathan Ashman, then assistant to the director of Mercedes-BenzUK, was a keen amateur rally driver who had given the 350 and 450SLCs their rally debuts, the latter on the 1976 Tour of Britain, and assisted Waxenberger in running the 5.0s on international events.

The three-speed auto was the strongest gearbox for the competition cars

“He seemed to have unlimited budget and authority,” recalls Ashman. “They could build anything he wanted. He led from the front and everyone had enormous respect because he worked tremendously hard and was very enthusiastic – although he tried hard to cover that up!

“He appeared to be extremely autocratic, but would listen to the drivers and take it on board. Everything had to be the best; on the Safari Rally he had a Unimog stationed at every mud hole.”

The works SLCs were equipped with rollcages, skidplates, bucket seats and even oxygen respirators for certain high-altitude South American events.

“The brakes,” recalls Ashman, “had a switch for turning the ABS on or off – or for the front only, so you could flick the back around corners.”

Perhaps more seen as an elegant grand tourer, the SLC was nevertheless a successful rally warrior

“They were remarkably trouble-free,” he continues,“apart from a problem with a rear stub-axle on the Safari.

“Because it was such an inherently strong, tough car, we needed to do a lot less to it. You could treat them really harshly and they were fine.”

Weight and size caught up with SLCs soon enough, however. On the Acropolis Rally the big coupés shredded their tyres; on the Rally of Portugal they were simply not nimble enough on the narrow roads, finishing fifth and sixth behind the winning Fiat-Abarth 131 Rally.

Luck then deserted the team even on the Safari Rally, where third was all local driver Vic Preston Jnr could manage in an event that played to the SLC’s strengths.

Mikkola’s second in Argentina on the Codasur was better, but still not enough to please Daimler management who took the view that if Mercedes was going to enter the motorsport arena, anything less than total victory was bad publicity and was, therefore, not worth the risk or the expenditure.

For a big and heavy car, the SLC has fine poise and balance

For 1980 the works cars, like the road cars, were badged as 500SLCs and were running in Group 2 because more than 1000 replicas had been built.

By then good for up to 329bhp, they went out on a positive note, taking first and second place on the 3000-mile Ivory Coast Rally – a setting that flattered the big coupé’s qualities of endurance.

Speeds topped 125mph at times, with averages on some sections of 75mph, ensuring that Mercedes came an honourable fourth out of 16 in the 1980 championship.

The SLC’s pillarless profile

The 500SL had been earmarked to take over from the soon-to-be-discontinued SLC in 1981 as the brand’s rally weapon.

Four cars were prepared and Waxenberger even hired Walter Röhrl to drive them, luring him from the winning 1980 Fiat team with a $10,000-per-drive contract.

But when the young German ace tested the shorter, lighter but more skittish 318bhp two-seater he realised that it was likely only good for a fourth or fifth place on the Rallye Monte-Carlo against increasingly specialised competition from Audi and Lancia.

Perfect for the open road

The 5-litre SLCs totalled 2769 cars, split 1636/1133 between the 450SLC 5.0 and the post-1980 500SLC with its V8 reduced slightly to 4973cc (for Group 2 eligibility) and the later four-speed auto.

The 450SLC5.0 ran from September 1977 to March ’80; the 500 from there through to the end of production in ’81.

Both models came with discreet bib and boot spoilers (although customers could remove the rear lip if they didn’t mind losing the aluminium lid in the process), and the lower flanks below the rubbing strip painted in a contrasting grey.

The ‘Mexican hat’ alloys looked the same as the standard SL/SLC type, but had a ½in wider rim. Most cars were supplied without sunroofs, and even headrests, headlamp washers and central locking were officially extras.

These ‘Mexican hat’ alloys have a wider rim than stock

These lightweights were sold mostly on the German market and across Continental Europe, in left-hand drive only, at a price that compared closely to the contemporary Ferrari 308GTB.

Around 40 500SLCs are thought to have sneaked into North America as grey imports and while they were never marketed in the UK, they do turn up.

Not long ago I remember talking to a car cleaner who worked for an Audi dealership and managed to nab his 5-litre SLC for a song after it was chopped in against a modern blob.

Paul Deacon has owned his 450SLC 5.0 for two decades. He feels guilty he has not used the silver coupé as much as he should have, with racing pedal bikes having become an all-consuming passion in the intervening years.

The big SLC wasn’t as nimble as its rivals

“The attraction of the 5-litre stemmed from a childhood encounter with the Mercedes-Benz in-house magazine in aller Welt, which had a piece on the 5.0 showing all the aluminium parts,” says Deacon, whose car came into the country from Germany with 99,000km in 1999.

He bought it from Michael Lavers at Silver Arrows a year later: “It’s my second SLC, because I was running a standard 450 at the time as a company car. With that you had to use the gearlever to row it along, but the 5-litre has more torque. It handles much better than an SL.”

It looks better, too. The shape gets prettier as the years pass, and Mercedes was correct in not besmirching its elegant profile with boy-racer addenda for this special edition.

That said, with its very ’70s green velour, massive wheel and token veneer trim, the ‘lightweight’ interior has none of the testosterone-fuelled sense of occasion you get upon stepping inside a CSL.

The huge steering wheel and corduroy trim give a ’70s flavour

On the road the SLC is quiet, capable and comfortable. Its fat seats are more embracing than they look, all-round vision is superb and you can drive it quickly at once.

It is probably faster than many more exotic contemporary machines that make a lot more fuss; press the firmly damped throttle and you merely swoop forward on silken elastic with a distant mumble of fuel-injected V8 throatiness that is never truly exciting but sounds satisfyingly efficient.

Turn that big wheel and you know right away that there is sufficient feel to inspire confidence in placing the SLC accurately without it being twitchy, although ultimate grip is moderate by current standards.

Had Mercedes homologated a really good manual ’box for this car, I suspect it would be a more valuable prize today.

You don’t see a 5.0 too often, especially here in the UK

As it is, the auto is about as good as it got in the late ’70s, with a certain crispness of response that tends to suggest it is not squandering huge amounts of power, and a willingness to be overridden that keeps progress interesting.

The brakes you don’t think about (which means they must be good), and if the taut ride doesn’t feel as expensive as you think it should that’s probably more down to road noise than a lack of resilience.

Given the rose-tinted mist that descends whenever talk turns to homologation specials, I have always been surprised at how reasonably priced these 5.0s are.

This is, I think, partly because people get understandably confused by Mercedes model numbers, and the SLC adds to the problem because of its visual kinship with the much more numerous and long-lived R107 SL.

Its clean, slim-pillared shape is acquiring grace with age

Then again, SLCs are not exactly rare, with 66,000 built, and even 5-litres are conspicuously numerous.

Perhaps the 5.0 turned the usual ‘homologation special’ story on its head by being more a tale of commercial success than on-track glory.

Only Mercedes could produce a low-volume, motorsport-inspired special so seamless and sensible that it was no more or less exciting, really, than the car on which it was based.

Images: Luc Lacey/Daimler AG

Factfile

Mercedes-Benz 450SLC 5.0

Sold/number built 1977-’80/1636
Construction steel unitary, with aluminium bonnet, doors and bootlid
Engine all-alloy, sohc-per-bank 5025cc V8, Bosch fuel injection
Max power 240bhp @ 5000rpm
Max torque 278Ib ft @ 3200rpm
Transmission three-speed automatic, RWD
Suspension independent, at front by double wishbones rear semi-trailing arms; coil springs, telescopic dampers, anti-roll bar f/r
Steering power-assisted recirculating ball
Brakes discs, with servo and anti-lock
Length 15ft 6½in (4740mm)
Width 5ft 10in (1778mm)
Height 4ft 3¼in (1300mm)
Wheelbase 9ft 3in (2820mm)
Weight 3340Ib (1515kg)
Mpg 15
0-60mph 8.5 secs
Top speed 140mph
Price new DM62,272 (1978)
Price now £35,000*