Citroën C5 2.0 HDi

The French car maker has turned it's ugly duck into a swan with this futuristic model that glides easily into the premium league

Price: from £17,500 approx (range starts £15,500 approx), on sale April

Engine: 1,997cc, four cylinders, 16 valves, turbodiesel, 138bhp at 4,000rpm, 236lb ft at 2,000rpm

Transmission: six-speed manual (six-speed auto optional), front-wheel drive

Performance: (manual) 127mph, 0-62 in 10.6sec, 47.1mpg official average, CO2 157g/km

Citroën C5? Isn't that the slab-sided car full of unrelated feature lines which sells for thousands of pounds below list price? Isn't it, in fact, Citroën's biggest clunker in years? Well, yes, if you're talking of the old one. But now there's a new one, and the ugly duck has metamorphosed into a swan.

Citroën has made some beautiful cars over the years. The beauty is usually highly unconventional, the better to complement the do-it-differently mechanicals, but it's the very functionality of the designs that underpins the beauty. The DS is an obvious example but the later CX and today's C6 continue the notion. And now we have this C5 – longer, lower, a little wider and roomier than the old one.

This time, the beauty – rare enough in an era of car design tending too often towards the brutish, shocking or contrived – is more artistic than functional. The C5 is meant simply to look nice. Its nose is typical modern Citroën. Its roofline is one arc, like a C6, but the flanks are more sculpted. Viewed tail-on it looks generic-modern, like an Audi or a BMW, but move off-centre and you see a rear window convex from the side, concave from above.

This concavity has echoes of the CX and C6 and increases the size of the boot opening, for the C5 is no longer a hatchback masquerading as a saloon. So far, so handsome, and there's a similarly good-looking estate car to come later this year which has wraparound rear lights and, optionally, a powered tailgate.

Now, one of the defining features of the larger Citroën has been its hydropneumatic suspension. It gives a very specific smooth, floating-on-fluid ride and keeps the car level under every sort of load condition. The system is very reliable nowadays, but fleet managers – the people Citroën wants to buy lots of C5s – remain suspicious of it. Nor do they see why they should pay extra for something they think they don't need and which other car makers manage without.

So – take a deep breath, loyal Citroënistes – the C5 can be had with proper hydropneumatics (called Hydractive 3 Plus, powered by electric pump and automatically firming-up in spirited driving) or with conventional steel coil springs. This isn't quite the extravagant duplication of engineering and production resources that it sounds, because the C5 is based on the shortened underpinnings of a C6 (with hydropneumatics), which shares many components with the Peugeot 407 (with coil springs). All three cars are made in the same factory at Rennes, in Brittany.

Buyers of this size of car often have in mind a kind of automotive apartheid in which certain German and Swedish brands are "premium" and nearly everything else is a bit short of status-enhancing ability. Yet the gap, real or imagined, is closing. Ford design chief Martin Smith told me that in Germany, the most status-sensitive of all the Western European nations, people who would never have considered a lowly Mondeo before are buying top-spec Titanium versions of the new one in droves.

Like the Mondeo, Renault's new Laguna has premium aspirations and a cabin well-suited to the task even if the exterior falls short. And now the C5 also joins the blue-card category of the executive club. Its cabin is heavily soundproofed – and the abundance of padding and soft-touch surfaces cossets you. The dashboard looks streamlined and futuristic, and top models have gentle ambient lighting at night under the dashboard's trim strip and diffused over the centre console. Optionally, you can have motion-sensitive lights which illuminate the door pockets as you place a hand within.

The most obvious bit of futurism is the fixed, non-rotating hub of the steering wheel. First seen in the C4, this houses buttons for the stereo, cruise control, computer and telephone. The C4's central, digital instrument display is not reprised here, though. Instead we see normal dials with needles visible around the periphery, Mercedes-fashion, while the dial centres are taken up with information displays.

Check seat adjustment. If it's a C5 Exclusive rather than an SX or a VTR+, the backrest curvature is adjustable as well as its rake. Move off; the electric parking brake releases, so it must be a Hydractive C5. Which means an Exclusive unless it has the 173bhp, 2.2-litre, twin-turbo, HDi diesel engine, in which case it could be a VTR+.

It is indeed an Exclusive 2.2 HDi, and it's effortlessly swift and serenely quiet. It does the usual hydropneumatic thing of moving languidly over undulations, flattening crests and filling in dips. It's a relaxing, if slightly unnatural feeling, and it's exclusively Citroën. Purists will be delighted.

Should you crave a tauter drive, you can press the Sport button and feel the suspension firm up, which means the serenity over small bumps suffers. Your choice. I also tried a C5 Exclusive with the 2.7-litre, 208bhp, V6 turbodiesel used in some Jaguars, and it made for a proper luxury car, if one that few will actually buy. As for CO2, at 223g/km it just avoids the £25 London congestion charge for "gas guzzlers".

Other engines include petrol units of 1.8 and 2.0 litres, plus a frugal (149g/km) 1.6-litre turbodiesel with 110bhp, but the most obvious engine in this familiar range of Peugeot-Citroën engines is the 2.0-litre turbodiesel with 138bhp. How this performs in a steel-sprung, fleet-friendly C5 will be a key factor in the car's success.

Well, it's fine. Not as energetic as the 2.2, but muscular enough if you make good use of the six-speed gearbox, and usefully economical. And the steel springs and conventional dampers alter its character signifi-cantly. It still rides smoothly, having softer settings than its more crisply responding Peugeot 407 cousin, but it does so with a more familiar motion which doesn't try to redraw the road's top-ography. Some will prefer it, especially those who enjoy a brisk, rewarding drive. The steel-sprung C5 is easier to understand, because the mystique has gone.

Maybe that makes it less of a Citroën, but it's more of a car for those scared of Citroëns up until now. I just hope its credibility isn't crushed by discount fever – the kiss of death to aspirations of prestige. The new C5 deserves a better fate.

The rivals

Ford Mondeo 2.0 TDCi 140: from £17,395

Largest, widest, roomiest car in the class because it shares underpinnings with the S-Max MPV. Refined, capable, good to drive, not the smoothest over bumps.

Mazda 6 2.0D 140: from £18,420

Highly impressive new car from Mazda delights keen drivers with responsive handling and excellent ride. It's well-equipped, quiet and powered by a good diesel engine.

Renault Laguna 2.0 dCi 150: from £17,650

New Laguna is luxuriously modern inside, odd-looking outside, brisk and refined to drive. New 175bhp diesel option is effortlessly rapid.