MAXIMISATION of interior space was clearly a major objective with the C5's designers, so the car accentuates the vertical more than has been common with past Citroen sedans. The doors are also very flat in cross-section, with minimal "tumblehome" (the curvature of the body sides) to maximise interior width, especially at head level. The A-pillar sweeps well forward too, almost in MPV style, to create an impression of space within the cabin.

The aerodynamic figure is good, without being anything special by today's standards at 0.30Cd. The rear of the C5 is styled to make it look more like a sedan than a hatchback, while the short rear overhang and extended front are typical Citroen - although the tall roofline is anything but.