The cars : Citroën SM development story

Carole Nash Classic Insurance Specialists

Keith Adams tells the story of the Citroën SM – the short-lived French flagship, built between 1970-1975, and which still leaves a lasting impression today.

Such glorious possibilities

When Citroën first set about creating a new French national flagship, it was with the very clear view of reliving the glorious pre-war grandes routières built by Bugatti, Delage and Talbot-Lago. Beyond that, the bosses at the most innovative of French companies was also well aware that there was a vacuum at the top of the market left by the departure of Facel Vega.

Taking the Deesse concept of 1955 and uprating it into its greatest form – the Citroën SM – ready for the 1970s, was the company’s typically bold response.

From the wish to produce a more powerful DS sprang the SM. Ordinarily, taking an ageing middle-class saloon and trying to create something special from it would result in disappointment.

Starting out with the DS

These short-wheelbase DSs proved very capable testbeds for Projet S, the new Citroen SM.
These short-wheelbase DSs proved very capable testbeds for Projet S, the new Citroën SM

But when that car was as daring and adventurous as the DS, there’s a certain logic to such a decision. Thanks to its low-slung proportions and daringly swooping aerodynamic body, it looked like nothing else on earth. And that’s how Project S, what would ultimately become the SM, started out.

Early prototypes were built upon shortened cut ‘n’ shut DS models (above), which ultimately proved themselves in motor sport. The key to Projet S‘s genius was its technical make-up – Hydropneumatic interconnected suspension and powered disc brakes gave the DS a genuinely exotic feel. Citroën knew it could replicate that in a more upmarket version.

The only fly in the ointment was that, in the 1960s, it didn’t have an engine up to the task in its model range. The DS’s power unit was a very capable overhead value unit, with its roots in the pre-war but, if Citroën was going Jensen hunting with its new car, it would need a much stronger engine. Initial studies centred on a new six-cylinder engine, developed in-house.

The Maserati connection

The question of how to create a suitable engine more quickly was answered in January 1968. These were expansionist times for the major car manufacturers, most of which were going through a ‘grow or die’ period. Corporate mergers were all the rage. In the UK, that led to the creation of British Leyland, whereas, in France, it led Citroën to even less logical conclusions.

To outsiders, Citroën’s riposte to the mood of the moment was baffling to say the least. Pierre Bercot (below), the company’s Michelin-appointed Managing Director pushed ahead with his own expansionist policies. The company purchased a controlling interest in Maserati, industry watchers wondered why.

That’s probably because Citroën was stretching itself elsewhere at the same time: the company purchased Berliet and Panhard and also formed joint ventures with NSU (forming Comotor to work on Wankel engines) and Fiat (to form the short-lived Pardevi company).

Citroën boss Pierre Bercot pushed a policy of expansion, which ultimately led to the purchase of Berliet, Panhard and Maserati…

However, for Citroën, Maserati’s integration into the family made perfect sense: it focused Projet S, as the Italian marque would build its engine, stalling plans for a triple-rotor Wankel in the process, and putting the in-house flat-six under intense scrutiny. More’s the pity…

Super engine for a new super-car

Within days of the takeover, Citroën abandoned Walter Becchia’s continuing six-cylinder powerplant programme. Instead, Bercot tasked Maserati with developing a new V6 for the SM. Maserati’s Chief Engineer, Ing. Giulio Alfieri, set about designing a fresh unit from scratch using the Indy V8’s tooling. It needed to be compact and light to work with Citroën’s traditional FWD layout, which forced the gearbox forward of the axle line, effectively turning it into a mid-engined car.

Turning the 4136cc Indy into a sub-2.7-litre V6 to fit into France’s 15CV puissance fiscale tax band required a shorter-throw crankshaft and a reduction in stroke from 85 to 75mm.

A one-millimetre smaller bore size was the last change needed to get the capacity down to a tax-friendly 2670cc, although further work was essential to allow the engine to work with Citroën’s twin-shaft five-speed manual gearbox – the same unit that would end up being used in the Lotus Esprit.

Citroën SM: Suitably exotic power

The Maserati-developed V6 was certainly advanced – and so it should have been, effectively being three-quarters of a supercar motor. It was all-aluminium, had quad camshafts and, at 140kg dry, it was exceptionally light.

Being based on the V8 left it with a 90-degree vee-angle, which was far from the ideal 60-degree that V6’s favour. Conceptually, that was how it was going to be – the Indy V8, simply shorn of two cylinders – but, as things turned out, it ended up being all new apart from the cam followers.

It was a remarkable achievement by the Italians. Alfieri had been given six months to come up with the first Indy V8-based V6 prototype, and he did the job in three weeks. His target was to produce an engine with 150bhp, yet in the end the offbeat V6 was capable of delivering 200bhp depending on camshaft profile. In production form with three Weber 42DCNF2 carburettors, it would make do with 170bhp.

Revolutionary evolution

As for the rest of the SM’s technical package, it was a mixture of DS carry-overs and innovations, and not further revolution. However, as the 1955 car was so far ahead of the game anyway, the SM would still emerge as a machine that was at least 20 years before its time.

Suspension was a refined version of the DS’s Hydropneumatic set-up, while the braking system remained powered by the suspension hydraulics; it now had discs all round instead of a mixture of discs and drums.

Diravi steering boasted two turns from lock-to-lock, fast by today's standards.
The Citroën SM’s DIRAVI steering boasted two turns from lock-to-lock, fast by today’s standards

The main innovation was the steering. The SM’s powered system was known as DIrection à RAppel asserVI – DIRAVI, and was a speed-sensitive set-up which was distinguished not only by its super-high gearing of two turns from lock to lock, but also by its hydraulically assisted self-centring. The system’s party trick was that it would always pull the wheel to the centre, engine running or not – not that you’d want to do that on a regular basis.

And the faster you went, the heavier it became. Sounds artificial but, as we will see, it works a treat on the roads.

Geneva 1970: breath-taking Citroën unveiled

On the Citroen stand in Geneva and the SM makes its world debut
On the Citroën stand in Geneva and the SM makes its world debut

As for the styling, Citroën really wanted to make a massive splash. Although at the time of the car’s launch no single designer was credited, it’s now known that the SM was mostly the work of styling chief Robert Opron.

As a piece of design, it remains a true love-it-or-loathe-it effort – the long nose, curved rear window and drooping tapered flanks take some getting used to. It also has good and bad angles. Yet there was no denying its aerodynamics – in the wind tunnel the original model boasted a drag coefficient of 0.25, while the production car was nearer 0.34 (still better than the much-lauded 1983 Ford Sierra).

But thanks to a glazed and grille-less front-end dominated by six Cibié halogen headlights – with the inner two set up to swivel with the steering, allowing you to see round corners – it had huge autoroute presence, with little chance of being mistaken for any other car.

A massive splash from Paris

Paris Motor Show 1970
Within this scrum in the 1970 Paris motor show lay a Citroën SM. It was the star of the show, by some margin
By the end of 1970, Citroen had these two cars - the SM and GS - in its range, making it the most forward-looking of all European carmakers at the time.
By the end of 1970, Citroën had these two cars – the SM and GS – in its range, making it the most forward-looking of all European carmakers at the time

The latter stage of Projet S development programme was completed in remarkably little time. Barely more than two years after the French company’s purchase of Maserati, it debuted the SM at the Geneva Auto Salon.

The press and public were blinded by science, especially as the car was displayed alongside the equally futuristic GS – the gap-filling family model (which also rode on Hydropneumatic suspension and sported a Kamm-tailed wind-cheating body) that showed the world Citroën really was at the cutting edge. And in the spring of 1970, the SM was as cool as Brigitte Bardot in a little black Chanel dress.

Of course, in the starry-eyed optimism of the opening weeks of the new decade, the SM really did appear to have it all.

Citroën SM on the road and track

Citroen SM on the 1971 Michelin press test day. John Bolster is driving...
Citroën SM on the 1971 Michelin press test day. John Bolster is driving…

The first road tests appeared in 1970 – both Autocar and its weekly rival Motor decided not to wait for the UK cars to arrive. In both cases, performance figures failed to match up to Citroën’s claims for the SM.

When the magazines strapped their testing gear to the SM, its allure weaved a spell that had them reaching for new superlatives, despite disappointing performance figures. Enthralled by unheard-of levels of straight-line stability, combined with ultra-responsive steering and brakes, Autocar magazine spoke in terms of being able to fling the SM around ‘like a Lotus Elan’ in tight corners.

However, the Citroën gave out mixed messages which the road testers took time to understand fully. DIRAVI was a new experience, and seduced them into thinking the model handled like a sports car – yet, in reality, the SM still understeered and rolled like a DS – perfect for France’s heavily-cambered back roads.

It’s just that with two turns from lock to lock and artificial feel through the small, fat, single-spoke wheel, the steering was telling fibs. However, to rough-house the SM was to entirely miss the point.

Good and bad in competition

Citroën SM guru, the late Andrew Brodie, proved the car’s ability on road and track. ‘Team Brodie won the 2007 Tour Auto Regularity using my SM, with Bob Linwood driving and his wife navigating.

We came second equal in Tour de España, and last year won Tour Britannia, so the car can’t be as bad as some people reckon,’ he said. ‘It is the finest GT ever made. No vehicle has the dynamics of the SM, and you won’t find another that steers as well. The faster you go, the more confident you get.’

And that’s the point. It was – and remains – a GT car par excellence. ‘The difference is the straight-line composure,’ Brodie continued. ‘You don’t come off on bends, either, and it doesn’t wallow.’

Citroen SM wasn't a success on the Avon Tour of Britain, with Ray Hutton and Howden Ganley sharing driving duties.
Citroën SM wasn’t a success on the Avon Tour of Britain, with Ray Hutton and Howden Ganley sharing driving duties

Autocar magazine ran one in the 1974 BRSCC Avon Tour of Britain (above), and didn’t do quite so well, finishing near the tail of the field. The magazine’s Editor, Ray Hutton, rode alongside Grand Prix driver Howden Ganley, where they learned a lot about Hydropneumatic Citroëns.

After the event, Ganley concluded: ‘Now we know why people don’t race Citroëns!’

Driving an SM – a star of the 1970s

In 1974, at the end of his 10,000-mile long-term test, Autocar Editor Ray Hutton said: ‘Altogether the SM is an odd amalgam of characteristics. Its startling, super-streamlined body couldn‘t be anything but a Citroën and its aerodynamic efficiency, shown by its maximum speed and lack of wind noise, are what one would expect from the flagship of this very imaginative firm.

‘The Maserati V6 engine emits a splendid racing growl under hard acceleration and has quite a harsh feel to it when working hard. Similarly, the manual five-speed gearbox has a precise “gated” change that would not be out of place in an Italian sports car’ – Autocar magazine

‘Somehow, with such a futuristic appearance a conventional power unit and transmission seems out of place; it deserves a gas turbine and fully automatic transmission at the very least.’

Despite reliability issues, he loved the car, and concluded: ‘As enthusiasts we have tended to dwell on its technical marvels but let us not forget that as an attention-getter the SM is supreme.’

In its December 1971 issue, CAR Magazine compared the SM with the BMW 3.0CS and called an easy victory for the French car. It wasn’t perfect, though: ‘The main snag with the Citroën is the fact that it will not be available with right-hand drive for some considerable time, so those who are brave enough to buy it in LHD form will have to suffer.

‘However, the SM offers an almost incomparable ride, top-class steering, braking and handling, a punchy if noisy engine, and futuristic appearance inside and out. On that basis can there be any choice but the Citroën SM?’

Driving an SM today – still a modern experience

Driving a standard example today takes much less getting used to than it must have done in the early 1970s, yet you still need a mental reboot to get the best out of an SM. It’s a wide car, and outward visibility isn’t its strongest point, but it’s the steering that will dominate your impressions. The set-up is delightful and cerebral – on the road, you’ll rarely need more than a quarter of a turn, but the hypersensitivity discourages a lazy driving style.

Instead, you’ll be inclined to hold the wheel at the ten-to-two, and never will you want to drive one-handed (because the weight of resting a single hand on the wheel will have an SM turning), or allow the wheel to slide through your fingers exiting a bend, such is the strength of the self-centring. As for attacking bends, you feed the car in, allowing it time to settle into its roll angle; pitch an SM in, and it’ll lurch in an unseemly way.

‘That slightly offbeat-sounding V6 was more than man enough for the routes nationales and autoroutes you would enjoy on the way down to the south of France.’

Compared with the GT price opposition of its day, such as the Jaguar E-type Series 3 and Jensen Interceptor, the SM was considerably down on power. A standard 0-60mph time of around nine seconds was middling at best, although the 137mph maximum speed was exceptional for a 170bhp car of this size.

But that slightly offbeat-sounding V6 was more than man enough for the routes nationales and autoroutes you would enjoy on the way down to the Côte d’Azur. And although overtaking in an SM was harder work than in its muscular British rivals, holding high speeds and maintaining your averages was easier thanks to its overall levels of chassis refinement.

And nothing else on earth looks like an SM. As Ray Hutton said in 1974: ‘Even in France it turns heads and, in the little villages of La Mancha in Central Spain, the inhabitants treated it with the suspicion and wonder of something from Outer Space. It is a strange mixture, the SM. Mechanically ornate; simple in line; beautiful yet functional. A girl friend of mine described it as “the sexiest car in the world”. I know what she means.’

Fleeting success followed by disaster

Citroën gave up on the idea of importing right-hand drive SMs early in the production run – so, this UK press shot of a 1971 example is stubbornly LHD

Yet, the SM enjoyed only a fleeting honeymoon in the marketplace. This was probably because its appeal was more limited than Citroën had ever anticipated. In 1971, the model’s first full year of production, 4988 rolled off the line – but, in 1973, when the effects of the world economic crisis were beginning to affect all large car sales, that total dropped to 2619.

And the following year, when Peugeot wrested control of Citroen from its long-time partner Michelin in a Government-brokered deal, production fell off a cliff to a mere 294. It looked like the game was up by that time.

However, by then, Citroen was fighting for its very survival thanks to its loss-making habit, an inability to amortise the SM and GS’s development costs and tooling up for CX production.

Reliability issues soon spread

Even while the car was in production, it was earning a reputation for unreliability – and not from the complex suspension system which lay-people continue to fear to this day, but due to the Maserati engine.

The weakness of the rear timing chains that drove the V6’s overhead camshafts was well documented, and word soon spread that the SM was a fragile beast. The oil pump and ignition system were also failure-prone, as was the air-conditioning.

Citroën’s response was to sweep the problems under the carpet, and it wasn’t until much later, when the specialists got their hands on the SM, that these issues were resolved. Had it survived the 1975 Peugeot takeover, the model might have recovered with factory fixes, but that’s a matter for conjecture now.

Yet the reputation for fragility stuck and, even today – nearly 50 years on from its launch – enthusiasts will shy away from an SM, afraid of its engine and worried the suspension system won’t work. That’s probably why the French masterpiece remains such an underrated commodity, but the truth is that the SM is a dependable car for an understanding owner – and one that’s just so magnificently cool.

Limited development of the promising concept

Despite huge investment in the project, Citroën developed the SM sparingly. Electronic fuel injection arrived in 1972, upping the top speed to 142mph, and a 3.0-litre auto version was added the following year – but that was it.

The SM’s high-pressure hydraulics found their way to the Maserati range – with DIRAVI making the Khamsin uniquely responsive at the helm in the supercar set – and its engine was installed in the Bora to create the Merak. Yet remarkably little of the SM’s technology, beyond its wonderful DIRAVI steering system, filtered into the rest of the Citroën range.

The Maserati Khamsin ended up using the SM’s high-pressure DIRAVI steering system. The Merak sister car used its 3.0-litre V6 engine – but this was about the sum total of Maserati’s benefits from its short-lived Citroën tie-up

There were SM-based specials produced by third-party coachbuilders, though. Long-time Citroen partner Chapron, built the Mylord convertible and Opera saloon, as well as a pair of presidential limousines for the palace. Heuliez made the SM Espace – a clever open-topped version with a Triumph Stag-like T-bar roof and sliding roof panels.

Ligier built the SM-engined JS2, while Maserati used its V6 in the Merak and short-lived Quattroporte II. But as nice as these were, they were simply a glamorous side-show to this tale of woe.

Peugeot’s accountants call time on the SM

As nice as it was having a national flagship, the SM was nothing more than a high-profile loss-maker in the eyes of Peugeot’s accountants. Citroën had seen the dead hand of its new master being readied to kill the SM, and tried to head it off by setting up a deal with Ligier to quietly build the model at its factory in Abrest.

However, the arrangement took time to establish, and Ligier produced a mere 135 examples before Peugeot finally axed the SM – after off-loading Maserati in May 1975. Once that decision was made, the bosses didn’t even allow Ligier to assemble the final few unfinished cars, ordering them to be sent to the crusher instead. And that was it: the SM was dead after a mere 12,920 had been built during a five-year production run.

It would be easy to blame the First Oil Crisis and a stumbling world economy for the death of the SM but, in reality, it was a car that few really understood. And even fewer actually lived the romantic Nice-by-lunchtime lifestyle for which the model was so clearly conceived (and which was so beautifully captured in Citroën’s brochures and press photos).

Keith Adams

Keith Adams

Editor and creator AROnline at AROnline
Created www.austin-rover.co.uk in 2001 and built it up to become the world's foremost reference source for all things BMC, Leyland and Rover Group, before renaming it AROnline in 2007.

Is the Editor of the Parkers website and price guide, formerly editor of Classic Car Weekly, and launch editor/creator of Modern Classics magazine. Has contributed to various motoring titles including Octane, Practical Classics, Evo, Honest John, CAR magazine, Autocar, Pistonheads, Diesel Car, Practical Performance Car, Performance French Car, Car Mechanics, Jaguar World Monthly, MG Enthusiast, Modern MINI, Practical Classics, Fifth Gear Website, Radio 4, and the the Motoring Independent...

Likes 'conditionally challenged' motors and taking them on unfeasible adventures all across Europe.
Keith Adams

21 Comments

  1. It’s amazing to think how Citroen produced almost at the same time the GS & SM both so far ahead of their time both with new engines as well. Fifty years later Citroen is an excitement free zone with mechanicals and platforms shared with Peugeot,somehow in the next half century I doubt that we’ll be celebrating either the current Citroen range or it’s “premium” companion range DS.

  2. Read that the V6 was also to feature in the Lancia Stratos at one point via Citroen”s connections with Fiat at the time, when Enzo Ferrari finally allowed the Dino V6 to be used. On top of a development of the V6 later receiving twin-turbos for the Maserati Biturbo, there were also plans to develop a 4-litre V8 from the V6 for the Maserati Quattroporte II that was tested in a Citroen SM prototype.

    Prior to Peugeot killing off the Citroen SM, there were plans in the works by Heuliez to develop a cheaper Citroen SM using chassis and engine of the Citroen CX (with possible scope for using some version of the PRV V6) though nothing became of that project.

  3. The engine’s weakness came from its main architectural difference to the V8. The V8 had its cam chains at the end of the engine whereas the V6 had an intermediate shaft running the full length of the engine, driving the hydraulic pump and air con compressor at the front. From this shaft the cam chains were driven halfways down the engine’s length, forcing the chains to take a very unfavourable route through the heads. The contact area between the inner (intake) camshafts and the chain was a mere three teeth on the sprocket, leading to quick wear. The short chain driving the intermediate shaft from the crank was not up to the task of driving all the engine’s ancillaries. It stretched badly and additionally wore its tensioner out in no time, leading to disastrous effects in the engine. Improved versions for these chains are available nowadays, but the cam drive remains its Achilles heel.

    The SM had some aspects that looked like it hadn’t left the prototype stage. The battery is accessible after taking off the left front wing, if too much pressure is exerted on the end of the rear hatch this has a tendency to bend or snap off, making the window fall out.

    Citroen did not sweep the problems under the carpet. Updates to the SM were delivered in short intervals, but as was to be expected the dealers couldn’t be bothered to read the informations and do the work. For example, the SM used the differences in friction between the windscreen wiper blades and a wet or dry screen to automatically regulate the wiper speed without needing a rain sensor. This system should have been updated several times but in most cases wasn’t due to dealer indifference.

    Peugeot did put an end to the SM’s problems in their particular way. They made sure the last bodies were crushed and the remaining brand new and perfectly good engines were thrown off a high building’s roof just to make sure they were unusable.

    In the end, the SM was a triumph of technology over common sense.

  4. Citroen managed to unintentionally paint themselves into a corner in the early 1970s by developing too many technically complex models in a short time.

    There were a few never built versions of the SM, including a 4 door limo, which at least made it as far as a prototype or 2.

  5. Another casualty of the Citroen takeover by Peugeot was the GZ Birotor the Wankel version of the GS of which less than a thousand were built,I believe that the great majority of them were bought back by the company so that they didn’t have to provide service back up for it

      • Citroen went in partnership with NSU to produce the Comotor Wankel engine and NSU did make a fair effort in attempting to sell the Ro80 as it was on sale for almost a decade.If you’ want to see a truly hideous vehicle fitted with the rotary take a look at the M35 a coupe version of the Ami produced by Citroen to test out the new engine

  6. Stunning car, I’m not sure any modern cars turn heads like the SM.

    A shame the in house flat 6 was dropped in favour of the Maserati unit, the CX needed a better power unit

    • The CX was originally planned to have the Comotor twin rotor Wankel engine that was used in the GS Birotor and in the Van Veen OCR 1000 motorcycle.

  7. One of the main problems for this car was that it could not be sold in the US, due to the issue of it’s front end. The largest market for GT cars was the US, and without this market in the fuel crisis the car didn’t really have a leg to stand on.

    • But the SM *was* sold in the US. It lost the headlamp glass covers and had round sealed beam headliamps. http://images.classiccars.com/classifieds/171982_11070678_1973_Citroen_SM.jpg
      More of a problem was that in the US the Hydropneumatic was even less understood than in Europe and that for whatever inbconceivable reason Citroen was not allowed to use the green mineral oil based LHM hydraulic fluid in their US market cars (*afair* it was not allowed to have mineral oil as a brake fluid in the US), being forced to use the old red synthetic LHS fluid that created all kinds of problems because it basically was brake fluid and therefore highly corrosive.

      • Like the Rover SD1, the conversion of styled aerodynamic headlights to sealed beams did nothing for aesthetics.

        I’ve seen pictures of US spec SMs where the plate is behind the glass, others where the plate is mounted conventionally on the bumper.
        Where there is no plate, I’ve seen a large “Citroen” plate, or one which did away with the glass and fitted a 3rd pair of sealed beam driving lamps.
        I’m guessing state laws would dictate whether the plate could be behind glass etc.

        The main issue Citroen had with the US market of the late 70s was 1974 (MY) bumper regulation. This stipulated that bumpers had to be a constant height. With the hydropneumatic suspension sinking at rest, it wasn’t worth importing any more, the last US market SMs ended up in Japan.

      • Was it a Citroen SM that Burt Reynolds pushes into a river in Mean Machine? French cars have never been popular in America due to their mechanical complexity and poor rust protection in the past. AMC did try to save themselves with a tie up with Renault to produce economy cars that failed big time and they were bought out by Chrysler.

  8. I don’t get the criticisms of the SM’s top speed. OK the 0-60 time was never Lamborghini class, but 142 mph for a 2.7 litre V6 in 1972 was still excellent, considering you’d get similar performance from an E Type Jaguar with nearly double the engine capacity, and far worse fuel economy. I don’t think the SM was ever designed to take on the Italian two seaters, it was an attempt to create a sophisticated grand tourer with links to Maserati.

  9. It’s sad that such cars don’t exist anymore, the elegant grand tourer coupe, with its own unique styling. The few coupes available now tend to look much more aggressive, with the invariable “tested on the Nürburgring” rock hard ride. Or are obviously saloon based.

  10. As this article makes clear, the SM was based on a shortened DS platform… The engine bay was large enough to slip a Maserati V8 into. I have seen a DS which had an SM engine. Now there’s a thing to conjour…

    • Read elsewhere of a Citroen CX being tested with a 2-litre 4-cylinder version of the 3-litre SM engine as well as the SM V6 engines themselves, the former is quite fascinating given Citroen also tested a Flat-4 that may or may not have been related to the Lancia Gamma’s Flat-4 engine prior to being forced to settle for a 4-cylinder with distant pre-war roots.

      It also seems the case the SM was designed to feature a 4-cylinder though am assuming it was from early on in the project when Citroen were debating whether to produce a lightweight 2-door SWB Sporty Coupe (with possibly a 130+ hp 2-litre Twin-Cam engine) akin to the DS Sport prototype or a Gran Tourer that eventually became the SM.

    • Citroen actually developed a V8 version of the SM engine (well, had it develop by Maserati). And this is not just an existing Maserati V8, but a tailored version. One such engine is installed in a SM and running.

      There was also a company in France who fitted Turbo-Diesel engines into the SM…

      • Heard about the V8 apparently it was intended for the Maserati Quattroporte II prior to Citroen’s problems, it seems it was easier to develop a new V8 than adapt the existing Maserati V8 to FWD applications.

        Interested to know more about the aftermarket French company who fitted turbodiesel engines into the SM, particularly what engines would have fitted into the engine bay. Guess the 120 hp 2.5 turbodiesel from the Citroen CX was out of the question.

        • The Diesel conversion was done by Georges Regembeau, a well known Citroen tuner (think Downton). Regembeau developed his own 4 cylinder Diesel engine already as a conversion for the DS. 1974 he put a 2.4ltr unit with 88PS into the SM. Later Turbo Diesel engines got up to 145PS – mated to a 6 speed box.

          He also improved the V6, both in reliability (chain drives and new cilynder heads) as well as performance (quotes are between 240PS in mild tune and up to 300PS).

          All this would well be worth its own story…

          • A bit confused about the origins of the diesel version of Citroen M-Series petrol/diesel engines, whether it was developed by Indenor or an in-house diesel project.

            Was the diesel / turbodiesel engine developed by Regembeau a clean-sheet design or derived from the existing Citroen M-Series engine in one form or another? Interestingly it seems a 165 hp 2.6-litres turbodiesel was developed by Regembeau.

            Heard the SM V6 was enlarged to 3.2-litres (roughly equating to a 4.3-litre version of the 4-litre V8 prototype) though wonder whether it was capable of further enlarged displacements of around 3.5-4.0-litres. Know the related 4.2-4.9-litre Maserati V8 was said to have unrealised potential for a maximum displacement of 5.2-litres.

            While Citroen had its problems and near-bankruptcy, what prevented Citroen from better utilizing the services of Georges Regembeau?

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