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The C5 will help Citroën boost its margins, providing buyers appreciate the efforts that have gone into improving the quality

Citroën wants the C5, which launches in April, to continue to move its brand upmarket. It needs to perform better than the old model. The large family car sector accounts for 21 per cent of sales across Europe. It is the premium models that make the most money in it.

The Mondeo is a direct rival and, thanks to revised styling, more equipment and improved dynamics, has been favourably compared to more expensive premium models such as the BMW 3-Series and Audi A4. Citroën wants the C5 to gain similar credibility, while retaining competitive pricing of €20,000 to €32,000. A basic-spec 3-Series, for comparison, sells for around €28,000.

But Citroën needed to work on managing costs. By 2010, PSA Peugeot Citroën plans to be selling 4 million cars a year, to have an operating margin of 5.5 to 6 per cent, and to be the European market leader in environmentally friendly cars.

The C5’s role in this ought to be in improving profits. Its development focused on quality and comfort, taking a different approach to suspension set-ups. PSA hopes that the C5 will win 10 per cent of the upper-medium segment, and has upgraded processes at Rennes, already its highest-quality plant.

The factory produces the group’s platform 3 upper medium and executive models. It has a capacity of 300,000 and can produce six models. From 2009, around half will be C5s.

Project director Joel Maynadier estimates that the car was four years in the making. After digital prototyping, Citroën took four key models and worked on developing a basic suspension set-up for each. “We looked at the 1.6-litre and 2-litre diesels, the V6 diesel and the 2-litre gasoline engines,” says Maynadier. “These constitute the heaviest, lightest and two best-selling models. During year two, we took this base data and extended it to all versions.”

The V6 is the only model that comes only with Citroën’s Hydractive hydropneumatic suspension. It was the only way to achieve acceptable comfort with such a body mass. Citroën has used hydropneumatic technology in its upper-medium models for more than 40 years, but the C5 will use conventional springs and dampers for mainstream variants. Double wishbone front suspension with the linked hub carrier of the 407, which boasts relatively little wheel axis offset, combines with a multi-link rear end.

The flexibility of PSA’s upper-medium platform 3 makes it economically viable. Although each model has a different wheelbase, the Peugeot 407, Citroën C6 and Citroën C5 all have commonality of around 60 per cent. The 407 uses conventional suspension, the C6 only Hydractive. “All the parts were already in the toolbox at the start of the project,” says Maynadier.

“The C6 suspension is the same, with only minor tuning to factor in the weight of the car. The 407 is not entirely the same – springs and dampers are different, and the steering gear is different,” says Maynadier. On the C5, Citroën uses the fixed-hub steering wheel arrangement, which necessitates alternative components. But shared parts still account for 60 per cent of production costs.

Refinement was key for the C5’s development. NVH engineer Samuel Lemaine says this was aided by the use of identical metal suspension components for all versions. The Hydractive variant only differs in the upper part of the front suspension, which is mounted higher to clear the spheres. “This means resonant frequencies are fixed,” says Lemaine. “It would otherwise have been very hard to develop the two cars to the same standard in the timeframe.”

The two different versions of the C5 differ in damping and low-frequency vibrations, but these differences are desired. “All the engineering teams within the technical centre were curious to see if we could make a conventional Citroën feel like a Hydractive machine. It was a big challenge,” says Lemaine.
The engines are the existing 1.6-litre, 2-litre, 2.2-litre and 2.7-litre V6 turbodiesel HDi units developed with Ford, while the gasoline range is, for now, comprised of the ageing 1.8-litre, 2-litre and 3-litre V6 PSA powerplants. The PSA-BMW range will come later in 2008.

The particular natural vibration characteristics of the 2-litre and 2.2-litre diesels led Citroën to develop an acoustic thermal exhaust shield specific to these models. Made from aluminium and damping fibre, it reduces exhaust and engine noise produced by the engine’s underfloor vibrations.

Lemaine says the main issue was wind noise – the windows are larger and EU legislation is forcing larger external mirrors. Development to reduce this was conducted in a double-glazed C5 model as the background noise base was lower. This made it easier to eradicate more noise sources, and so models without double glazing are quieter too.

“Road noise was calculated on virtual prototypes,” says Lemaine. “We know how to make the axle vibrate to see how the body reacts.”

Real-world testing took place on surfaces with graded, large-diameter stones of between 5mm and 20mm. These are particularly noise-inducing and led to the introduction of a new type of wheel-arch covering. The four-layer textile fibre guards were developed in association with Michelin, which also supplies the 16- to 19-inch tyres.

“There’s little difference in road noise between the 16-inch and 17-inch tyres,” says Lemaine, “but it’s harder to make 18-inch tyres quiet because of their width and aspect ratio. We were worried about noise from the 19-inch tyres. But we were surprised by how small the difference over the 18-inch is.”

The company showed the production version of the C5 early on. “We wanted real customers to treat it as their own car,” says Maynadier. “We sent 250 finished cars to Paris and Germany for road trials.”

Despite PSA’s aim to be a leader in environmental technologies, stop-start technology is so far absent on the C5. “We’ve had a bad experience with this,” admits Maynadier. Citroën brought the technology to market early, in the C2 and C3, yet sales were a significant failure.

“These are models for town, where vehicles can be stopped for over half the journey time. It’s a positive addition, but we still didn’t hit targets,” he says. “The C5 is a highway car and, with the extra weight of the stop-start technology, overall consumption could have been affected.”

A diesel hybrid isn’t on the cards. “The first car to receive this technology will be platform 2 models: the Citroën C4 and Peugeot 308,” says Citroën managing director Gilles Michel. “Besides, no one else will launch a hybrid in this segment in 2008.”

Instead, extra fuel savings will come from the tyres. By the end of 2008, there will be a HDi 110 version running on Michelin’s low-rolling resistance Energy tyres, which should improve the 5.6l/100km fuel consumption by around 3 per cent and reduce carbon dioxide emissions to around 140g/km.

Inside the car, Citroën is using LED mood lighting to add to the sense of occasion. The dials have annular needles controlled by tiny motors. The fixed-hub steering wheel has buttons with a silicone skin covering.

It’s going to take time for Citroën to become accepted as a premium brand. Bringing dealerships up to standard will be a key part of converting the public’s changing perceptions into sales, particularly if the company is to win more fleet sales. But having the C5 in the showrooms is a good next step.

Suppliers to the Citroën C5

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