5. Citroen C6:
The C6 was aimed as a stylish alternative to executive cars, like the Mercedes-Benz E-Class and BMW 5-Series. The C6 is a pretty innovative car with its rear spoiler that automatically adjusts to speed and braking, and heads-up display and xenon directional headlamps. They made only 23,400 units of the Citroen C6.
4. Citroen BX:
The BX is a large family car that was designed by Marcello Gandini. It largely resembled Volvo Tundra Concept, which was also designed by Gandini. BX was a success because they sold 2,315,739 units of the BX. There were many different versions like sedan, estate, van, Sport, GT, GTi, 16V and the 4TC. 4TC was a Group B rally car. Due to the Group B regulations, 200 street versions had to be build of the 4TC. 4TC wasn't very successful in rallies and Group B got banned. Only 62 road going 4TCs were sold because it had reliability problems. This led Citroen to buy back many 4TCs and get them destroyed. There are only handful of these left and these are highly sought after nowadays.
3. Citroen CX
Citroën CX is an executive car that was voted European Car of the Year 1975. Available models were four-door fastback, a station wagon and a long wheelbase model. There was also a more sportier model 25 GTi Turbo. CX was also in rallies like the Tour De Senegal and the Paris-Dakar. Nearly 1.2 million CXs were produced
2. Citroen SM:
Citroen SM was a grand tourer that had a Maserati V6. It was designed by Robert Orpon. The SM was pretty aerodynamic for its era, with Kamm tail and low drag coefficient of 0.26.
1. Citroen DS:
I would say it's the best ever Citroën with hydropneumatic suspension, or actually the best Citroën ever. Its design was ahead of its time. Designed by Flaminio Bertoni, the DS was successful at rallying and it even won the Monte Carlo Rally in 1959 and the 1000 lakes rally. DS won the Monte Carlo rally again in 1966 when Pauli Toivonen was the driver. 1,455,746 Citroen DS cars were made.