Citroën SM Buying Guide

Don’t be put off by unconventional styling and tech; the SM remains one of the most advanced GT cars ever built. Here’s what to look for

How much to pay

• Project £12,000-24,000 • Good £22,000-40,000 • Concours £40,000-60,000 •


Practicality ★★★
Running costs ★★
Spares ★★
DIY friendly ★★
Investment ★★★★
Desirability ★★

Launched in 1970, the Citroën SM is not a car you’ll find at the top of many people’s bucket lists. That’s a shame, because it’s one of the most advanced and charismatic models of its generation. It rides and handles like a Citroën, sounds and goes like a Maserati, and looks like nothing else on Earth.

The SM deserves its place alongside the E-type, Aston Martin DBS, Ferrari Dino 246 and Mercedes SL, not just because it’s a 1970s supercar, but because it went about its business in a way that no supercar before or since has ever done. Its motorsport history proves its worth, too. Values have been rising since 2015, but they’ve a long way to go yet. Read on to find out how to get a good one while they’re still relatively affordable.

Your AutoClassics Citroën SM inspection checklist


All SMs use a version of the Maserati V6, as found in the Merak. This engine is derived from the Maserati V8 used in the Bora, Khamsin and Ghibli, and was later used with forced induction in the Biturbo. In the SM, it comes with either carburettors or fuel injection, and as either a 2.7 or 3.0.

All fuel-injected cars – the most desirable model – used the 2.7-litre as dictated by French tax laws; the larger 3.0 was largely targeted at the American market. This engine is reliable in service provided it has received the right maintenance; check the service file for regular timing-chain changes. Fuel-injection hoses should be checked for leaks. A stainless steel exhaust is of benefit – these aren’t cheap to replace.

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The five-speed manual transmission used in the SM is sturdy, and is not known for any real reliability issues in service. It’s important, however, to ensure the oil has been changed on a regular basis. The gearbox is shared with early examples of the Lotus Esprit, and thus if any advice or repair work is needed there are scores of Lotus specialists who may be able to help.

We’d avoid the automatics for two reasons. Firstly, they’re less desirable for resale, and, secondly, the manual is a delight to use. With that in mind, however, we’d say that there are no reported inherent faults with SMs fitted with autos if adequately maintained. Many have reported weaknesses that can be traced to loose brake bands inside the transmission – these must be manually tightened each year. If the ATF is anything other than cherry red, there are potential problems and we recommend you look for another car instead.

Suspension and brakes

SMs use the famed Citroën hydropneumatic suspension system, with nitrogen spheres interconnected by LHM pipework. These cars all use LHM, unlike the similar DS, which changed fluid partway through production. Check that the suspension raises and lowers correctly; road imperfections should be very difficult to notice in a correctly functioning example.

Interlinked with the suspension system is the high-pressure, fully powered steering with powered return. This is not an assisted system, in that there is no direct mechanical link in usual operation. It should be light, yet firms up at speed to give confidence – effectively, the hydraulic system forces the steering to remain in the central position. It is imperative that this works, so put the car on lock in both directions and check that the wheel returns to centre.

The brakes are sharp, and care must be taken when applying them for the first time. Check for fluid leaks, as the suspension, steering and brakes are operated by a single hydraulic system. There are specialists who can help you tend to this, and sphere replacement is inexpensive if necessary.


Front and rear screens are bonded to the car, and both can create rust issues as a result. Removal to treat rust is difficult. The tailgate seals are notoriously poor. Issues here can let water into the car and cause corrosion issues – most notably in the boot floor region. Check this thoroughly for any signs of water ingress.

While you’re there, check the welds for signs of corrosion where the inner and outer rear wings meet in the back arches. You’ll struggle to find replacement panels, so it’s imperative they’re good. There may be galvanic corrosion between the aluminium bonnet and its trim strip at the leading edge, while there may be small corrosion holes in the bonnet itself. These can often be covered by paint, so check for paint defects.

Check the panelwork for any signs of filler or previous accident damage. Older paint is always good, as it suggests there is less to hide. Be suspicious of any fresh paint, unless there is proof of bodywork done to justify it.


Check that the seat adjusters work as intended. The mechanism is somewhat fragile and, if they break, repairs can be difficult. Retrim work is expensive but the materials are available if you want to do it. Cloth-trimmed cars have square blocks in the seats, while leather seats feature oblong blocks. If you see a leather-trimmed car with square blocks, or oblong cloth blocks, chances are the car has already been retrimmed at least once.

Unique items can be difficult to source. However, much of the dash and switchgear is shared with the equivalent Maserati Merak. Beware right-hand-drive cars; only three were converted originally, and chances are that any you now find will be subsequent conversions – these are less valuable than original LHD cars.


  • 1970: Citroën SM launched at Geneva Motor Show.
  • 1971: Pair of Presidential SM limousines built by Chapron.
  • 1973: Fuel injection fitted as an option, boosting power to 178bhp.
  • 1974: Automatic derivative launched.
  • 1975: SM discontinued and not replaced.

AutoClassics says

The SM is arguably the ultimate expression of Citroën’s technologically advanced approach. A front-wheel-drive GT in a class dominated by rear-drive heavyweights, it earned a name for itself in motorsport as well as among ardent Francophiles. Never before or since has a grand tourer been so technically audacious when compared with its contemporaries – and on top of that, you get that gorgeous Maserati V6 howl. If you can afford to buy one, do it now.


Citroën SM
  Power 170bhp
  Top speed 138mph
  0-60mph 8.4sec
  Economy 20mpg

Picture courtesy of MagicCarPics

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