It’s okay to question how, exactly, a Citroën ended up with a Maserati engine. From 1968 to 1975, Citroën owned Maserati, making such sharing a breeze between the two dissimilar automakers. The SM sported a 2.7-litre Maserati V6 engine producing 170 horsepower. Citroën derived the V6 unit from a Maserati V8.