From Citroen-SM-wiki

Contents 1 Maserati Merak (1972-1976) 2 Maserati Quattroporte II (1974-1978) 3 Lotus Esprit (up to 1987) 4 Ligier JS2 (1971-1977) 5 Matra (something)

Maserati Merak (1972-1976)

• Shared engine, trans, hydraulic system, dashboard (1977-82 did not use Citroën dash or hydraulics)

Maserati Quattroporte II (1974-1978)

• Shared Merak/SM 3L engine and Citroën transaxle
• Shared SM chassis, hydropneumatic suspension, DIRAVI steering

Lotus Esprit (up to 1987)

• Shared SM Transaxle with mods

Ligier JS2 (1971-1977)

• Shared Merak/SM 3L engine and Citroën transaxle

Matra (something)

Please revise - I have not found any connection between the Citroën SM and any MATRA