The C6 was inspired by the Citroën C6 Lignage prototype, which was first shown at the Geneva Motor Show in the spring of 1999, but can be differentiated due to a few minor details (such as the lack of suicide doors, which were present in the concept model).

[2] In isolation, the car's acceleration was regarded as "effortless" but not up to the standards set by similarly priced and equipped vehicles, such as the BMW 5 series of the era.

The C6 has a fastback saloon profile, which is due in part to the concave rear window that resembles the Citroën CX.

The C6 was aimed as a stylish alternative to executive cars, like the BMW 5 Series and the Audi A6, and it has been described as a "spaceship that rides on air", "charmingly idiosyncratic" and "refreshingly different".

[7] On an episode of Top Gear, Jeremy Clarkson tested the C6's Hydractive suspension by mounting a camera on it and driving it on the infield of England's Towcester Racecourse while filming a horse race.

Despite the bumps and potholes on the infield, the C6 managed to provide a comfortable ride and stable video coverage of the race while moving at 60 kilometres per hour (37 mph).

In July 2008, the C6 car configurator on Citroën UK's website no longer offered black as a colour choice for the popular Exclusive trim levels.

[citation needed] The 3.0 V6 petrol engine was discontinued in February 2009 – only the 2.2 and 2.7 HDi options with six speed automatic gearboxes were offered, in base C6 or C6 Exclusive trim.