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Citroên D5 : The star of the 2012 Mondial

Action Auto Moto

Please note: this is a work of fiction...

By Jean Savary – translated by Julian Marsh

Could this be the first offspring of the PSA-Honda marriage? Citroên finally seems to have come to terms with its past with the astonishing D5 revealed at the Mondial de l’Automobile.  Beneath its self-evident nostalgic styling, the D5 attempts to reinvent the automobile in much the way its ancestor did in 1955.  Indeed early examples of its ancestor have recently been officially classified as part of France’s national heritage.

With the launch of the D5 at the 2012 Mondial, Citroên is truly enjoying a cultural revolution.  Notwithstanding the disavowal of the dieresis in the founder’s name with its recent replacement by a circumflex (single chevron) accent, Citroên seems ready at last to acknowledge its troubled past.  And this new model represents a rebirth.  Not for them a mere styling revival like that of the Mini 1 and 2 or certain Jaguars.  This car resembles far more closely the remarkable reinvention by Fiat of the 500 and X1/9 or that of Saab with the 99 of 2010. Citroên timidly went there with the C3 which, if one squinted sufficiently hard, vaguely resembled the 2CV; the C4 which had a slight taste of GS about it; the C6 which hovered midway between SM and CX and let us not forget the C11 SUV with its trapezoidal grille which recalled the H Van.

The D5 which replaces both the C6 and C5 is not evocative like these models but represents a resurrection, reinventing as it does the DS which went out of production all of 38 years ago.  Its name inaugurates the use of the letter D, lifted from its predecessor while the letter S has become the number 5.  Accusations of mere nostalgia are overcome since with this new car, Citroên has renewed another of its traditions – that of technical innovation.  For the D5, it was not enough to follow Peugeot one year later with a Valeo gadget, nor to launch an “Evergreen” limited edition of the ageing C6 replete with Karaoke but to radically rethink the architecture, the mechanics and the interior. 

Underneath a beautiful retro dress designed by the new head of Style Citroên, Julien Jodry, the D5 is radically innovative.  With its rear engine and transmission; its double glazed windscreen; its domino layout seating for five; its 100% pneumatic suspension; and its safety innovations, the D5 recreated in the Grand Hall of the Mondial the feverish scenes that occurred at a certain Salon in 1955.  It overshadowed the C5 which has remained in production since 2008.

A rear wheel drive Citroên

With the mandatory fitting of antiskid technology (ESP) with effect from 2007, the conventional front engine layout is no longer viable.  The stability of a car is controlled electronically rather than being due to the weight distribution.  Furthermore, a front engine represents a major problem in the event of a collision and requires lengthy and heavy (and costly) frontal extensions to prevent the engine from entering the passenger compartment.  But this is not an “all at the rear” design like the 1939 Beetle or the small Renaults of the mid twentieth century; the D5’s transverse flat engine is placed forward of the transmission in the manner of the Porsche Boxster.  Another innovation is its mounting in a toboggan which allows it to move forwards and downwards in the event of a collision, thereby reducing the inertia in much the same way as that of the Smart.  The weight of the new continuous variation belt drive transmission, located between the driven wheels, is greatly reduced compared to that of a conventional transmission.  Despite the fact that Mercedes, long wedded to rear wheel drive, is converting little by little to front wheel drive (Class D and F), the use of rear wheel drive by the major proponent of front wheel drive comes as a surprise.  Nevertheless, it is totally logical.  In addition to the improvements in passive safety and habitability that this layout confers, there are benefits in braking thanks to the transfer of inertia to the front wheels as attested by many generations of Porsches.  There are also benefits in grip.  

Thus, placed very low, the engine and transmission help reduce body roll and also help maintain a very low body weight, not just at the front but in its entirety.  The bodyshell’s rigidity can be reduced since the engine and transmission provide much of the necessary structural rigidity.  Two long lateral aluminium “caissons” provide the requisite rigidity. Citroên claim that access to the mechanical bits is very easy when the car is placed on a hydraulic lift and there is a 100,000 km (62,000 mile) service interval for the HCDI engine.

A family of modular engines 

Let us refute the rumours of a six cylinder engine.  The French government ministry responsible for purchasing official cars has rejected all but the three cylinder hybrid HCDI versions.  Just like the DS, the D5 must forget its dreams of mechanical grandeur in the engine department but unlike its predecessor which laboured with the ancient Traction engine, the D5 will not use the antiquated engines that powered the C5 and C6.  Instead, a new range of dry sump engines, necessitated by its flat location has been developed.    In order to limit development costs, Citroên has developed a family of modular diesel engines with three, four or five cylinders, all of which share common components.  The three HCDI and the diesel/LPG (GNV) derivatives all have unique crankshafts and blocks but otherwise employ identical components although the peripheries obviously differ according to the engine.  Other innovations include piezo-electric valves from the Peugeot Formula 1 engines and the replacement of the turbocharger by a revolutionary helicoidal compressor (hélicoîdal according to Citroên).  The three diesels are respectively 1200cc, 1600cc and 2000cc developing 80, 100 and 120 kW respectively and offering typical fuel consumption of 4, 4.8 and 5.5 litres per 100 km.  The very low weight of the D5 (1100 kg) and excellent aerodynamics explain this sobriety.  

In this connection, D5 benefits from vents that evacuate hot air from the engine and also act as spoilers to improve the aerodynamics unlike the DS.  At speeds above 80 kph (50 mph), a plate slides closed in the manner of the air-brake of the Torpedo 909. The radiators are mounted laterally, behind the swivelling wings (those of the DS had to be removed to change a wheel), and are fed fresh air through the grill via side conduits and by two conduits arranged in the floor. As for the petrol versions, Honda retains exclusivity within the alliance but not having any flat engine available, they will eventually be replaced by versions of the four and five cylinders HCDI converted to GNV. Considering the low projected sales, Citroên does not seem to be particularly concerned and suggests that the new engines will be available at the end of 2013. Patience will be rewarded because they will generate 130 kw and 170 kw and record breaking consumption. Oh what fun one will be able to have on the No Limit motorways run by the Cofiroad and Britasf networks! 

A double windscreen for silence

The lack of a front engine ensures a great reduction in noise and vibrations and the double-glazed windscreen further reduces wind noise. Not a traditional double glazing set up but two windscreens, 2 cm apart, evoking the double rear window of the XM. The external screen being a conventional one made out of polarizing and athermic laminated glass, while the interior one being made out of anti-reflecting polycarbonate. In addition to its noise reducing qualities, this set up enjoys a high level of thermal insulation permitting the use of a less powerful air-conditioning system.  Misting up is not a problem either.

A domino seating arrangement

To distance itself from conventional saloon designs, the D5 does not copy the interior layouts of monospaces which supplanted them. It improves on them with an idea that will bring much user-friendliness on board: the central seat slides and swivels. Moved back, it forms a bench with the two others, sliding between them. By moving it fully forward (90 cm), the central passenger can join the passengers at the front and even stretch his or her legs, in this respect D5 resembles its ancestor which lacked a central console. Once centred, this seat with integral belt can be turned round to face the rear making it possible to converse with the two passengers in the back. All three individual seats may be easily folded and dismounted thanks to their monorail mountings as already seen on the new Renault Scespace to increase the boot capacity, The rear boot has a capacity of only 400 litres because of the “variator” or electronic control unit, but as one could expect, the bonnet  conceals a second boot of 300 litres, unless one opts for the RunFlat emergency tyre in which case the capacity is reduced to 200 litres. 

A hybrid version with integral transmission

Some D5 versions will however be front-engined – with two engines – one in each front wheel developing 30 kw each - the hybrid version Hy. Rather than a sophisticated transmission, whereby the driven wheels are powered by both a conventional engine and/or an electric motor as pioneered in the Prius, Citroên distributes them between front and rear.  Equipped with an integral transmission. D5 Hy will be electric powered up to 70 kph (44 mph) or under strong acceleration, and integral transmission beyond that. The three cylinders diesel only drives the rear wheels.  The alternator which charges the batteries is located under the front boot floor. The synchronisation of the two transmissions is managed by electronics - the variator – for example the diesel engine is engaged in slippery conditions. Thus equipped, Hy achieves 3,5 1 per 100 km on average or 4,5 1 as we measured it... It is hardly better than the 4 1 announced for the thermal HCDI 1.2 litre, but one can hardly compare the 80 kw of the latter with the total of 140 kw and 800 N m (81,5 mkg!) of the Hy. A more modest hybrid may be marketed in 2014 or 2015, once the mixed turbine GNV/gas oil brought in as a dowry by Honda has been fully developed. 

A 100% pneumatic suspension

Four wheel drive, self-levelling and variable ride height suspension (as on all large Citroêns since 1955) meant that Citroên had to battle with the ministry for the Economy and the Environment to exonerate its D5 Hy from the 4x4 tax since in high position, it can take on the most rutted surface. D5 gives up hydropneumatic suspension for an original 100 % pneumatic suspension which promises, in addition to new levels of comfort, some strange noises to judge some by the strange one hissing emitted by the beautiful one when the car was presented to the press. Unlike the BMW which has used pneumatic shock absorbers on its motor bikes since 2005, those of D5 are controlled via two bottles of compressed air supplied by a compressor, the noises of which will trigger familiar memories to those who had the privilege to pilot a DS. 

Less innovative since already seen in the competition

The D5 will offer some rather refined options. Thus, the electrochromatic glasshouse which switches from perfect transparency to total opacity in 6 seconds will be available, a whim of Julien Jodry imposed on Saint Gobain, to switch from black to a creamy white. An amusing detail, the rear view cameras are located where the DS placed its rear indicators. Two plasma screens were intended to replace the rear view mirrors but the Paneuropean Homologation Commission rejected this, as it recently did steer-by-wire, butter-derived fuel oil and TV screen windscreens. Traditional mirrors had to be borrowed from an old Citroên prototype from the early 21st century - Airdream. 

It remains to test the D5 on our good old Montlhéry circuit (recently classified as a world inheritance site by UNESCO) and maybe even on the road, as soon as one of our testers recovers his licence. It will be in our next edition, in the shops on November 24, 2012, and on your téléphonets the evening before.




Translation – JULIAN MARSH

Originally published by ACTION AUTO MOTO AUGUST 2005


Action Auto Moto