Aero evolution of the Citroën Xsara: from the Kit Car to the T4/WRC

The Citroën Xsara WRC is one of the most successful rally cars in the history of the World Championship, for what a review of the aerodynamics of the car, from the initial Kit Car model to the T4 (FRC) and finally the WRC was an absolute must.

The origin of the Xsara project as a rally car has to be found in the ban of the participation of Protos T3 cars (such as the Citroën ZX rally raid) in off-road races for 1997. The imminent launch of the Xsara road car required a motorsport specialty to market the car, and rallying was the most obvious alternative. The most logical step to start with was creating a Kit Car, a category cheaper than WRC that allowed the French manufacturer to concentrate their efforts in the main market, Europe.

As usual, Citroën Sport Technical Manager Jean Claude Vaucard (who had been previously working in the Peugeot 205 T16 and the ZX rally/raid) was charged with the design of the new car, with the support, amongst others, of Robert Choulet (Head of Aerodynamics at Peugeot Sport and Citroën Sport) and Laurent Fregosi (then Performance Improvement Engineer and future Technical Manager in charge of the design of the Citroën C3 WRC).

Citroën Xsara Kit Car

Testing of the car started in the same 1997, with Patrick Magaud and Michel Périn at the wheel. Based on the three-door road car, and initially using the engine of the ZX, the initial design included round, prominent front and rear fenders, as well as a rear wing with square endplates, adapted to the dimensions allowed for kit cars. The rear wing was supported by two arms connected under the wing.

Citroën Xsara Kit Car in the first development tests held in Col de Mens, France in 1997

Soon a more advanced aero package was installed, including a completely modified front bumper and side skirts. The new front bumper included a more prominent front splitter covering most of the front area of the car. The higher area was compensated with a smaller drag coefficient thanks to the rounded shape, in order not to increase drag.

Citroën Xsara Kit Car development test, France 1997 – image by Eric Claude Pierre

Also, the wings of the car were enlarged, so the fenders did not look so prominent from the front, while the view from the rear (see image below) confirmed the size of the modification.

Citroën Xsara Kit Car development test, France 1997 – image by Eric Claude Pierre

Under the car, some carbon fibre parts were added to make the undercar flat, thus allowing air to flow faster under the car (due to less friction with internals). The higher airspeed meant lower pressure, which turned out to increase downforce generation.

The car was thoroughly tested during the last months of 1997 and was aligned as course car in the 1997 edition of the Rally du Var, driven by Fabien Doenlen and Jean-Marc Andrié and already with the Citroën/Total decoration. Some days later, Chus Puras and Philippe Bugalski had the opportunity to first drive it in a test held in the Rally Catalunya special stage La Riba.

The car’s official debut took place in March 1998, at the Rallye Lyon-Charbonnières Rhône, where Bugalski/Chiaroni obtained the first win for the Xsara, while Magaud/Perin were fifth. The only visible modification on this car, with respect to the car seen in the last test was the addition of a small roof scoop.

P.Bugalski/J.P.Chiaroni, Citroën Xsara Kit Car, Rallye Lyon-Charbonnières Rhône 1998, 1st – image by Vincent Olympe

A few days later the car was homologated as a Variant Kit of the Citroën Xsara VTS (Homologation Form Nr. A-5583, Extension 03/01-VK) with the addition of new air intakes on both sides of the main intake of the front bumper, possibly for brake cooling.

Images of the Citroën Xsara Kit Car extracted from the Homologation Form Nr. A-5583, Extension 03/01-VK, April 1st, 1998

Once homologated, the car debuted in the WRC in the Rally Catalunya 1998, with Bugalski/Chiaroni, reaching an excellent final 5th position while  Puras/Del Barrio had to retire due to engine damage in an off. Both teams were able to set the fastest time in one stage, confirming the potential of the car and, most important, causing a first shock in the Championship.

The Kit Cars were lighter (max. weight 960 kg) than WRC cars (1.230 kg), while the difference in power was much smaller (officially 280 hp against 300 hp for the WRC cars, but both figures fall short from reality). The Xsara was also wider (max. width of 1855 mm against 1770 mm for the WRC cars) which made it more stable and equipped with highly sophisticated transmission (central differential). All these characteristics allowed Kit Cars to equal and sometimes be faster than the WRC cars, especially on dry tarmac.

P.Bugalski/J.P.Chiaroni, Citroën Xsasa Kit Car, Rally Catalunya 1999, 1st – image by Citroën Sport

The only aero modification of the Kit Car arrived in February’99 when a Variant Option was homologated to allow liquid cooling of the front brake calipers and the rear shock absorbers. That would result extremely useful on tarmac events to compensate for the excess heat generated by drivers’ use of left-foot braking (esp. Puras and, later on, Loeb).

Citroën Xsara advertisement after the first win in the World Rally Championship of the Kit Car

After several attempts, the wins of Bugalski/Chiaroni in Rally Catalunya’99 and Tour de Corse’99 (together with some podium positions achieved by the Peugeot 306 Maxi Kit Car) provoked many complaints from the official WRC teams. As a result, the FIA put some restrictions in place to reduce their competitiveness in 2000: weight was increased up to 1000 kg and power was limited. But, whatever the restrictions, Citroën was already working on the 4WD version of the car, whose first test was developed also in the spring of 1999, days after the win in Corsica.

Citroën Xsara T4 scale model test in the wind tunnel – image by Laboratoires Eiffel

Citroën Xsara T4

The 4WD version of the Xsara was initially named T4, where T stands for turbo (Garrett) and 4 for the 4WD (designed by Prodrive). With 300 hp power and 53 mkg of torque at 4000 rpm, the car had a total weight of 1230 kg, to fulfill the WRC rules. The aero package suffered important modifications, that were first evaluated with a scale model in the wind tunnel of Laboratoires Eiffel (Paris), the same facility previously used in the development of the Peugeot 206 WRC, amongst others.

 

Comparative between Citroën Xsara Kit Car (above) and T4 (below) – images by Eric Claude Pierre (above) and Manuel Madrid (below)

The car was presented to the public in May’99, with a modified aero that included many differences with respect to the kit car:

the bonnet vents (a) were relocated, as a result of the review of the internal flows, while a NACA duct intake was initially previewed, but finally discarded,

the front bumper was redesigned, especially at the level of the lower lip (b), a bigger central air intake (h) and with two vents (c) on both sides of the bumper, to remove air towards the sides of the car

the design of the side skirts (d) was also modified, to make them thinner on the rear end (compared to the design the kit car), while the rear bumper was extended at the bottom (e)

a new rear wing (f) was introduced, with the max dimensions allowed for a WRC car (max. width 1354 mm). The upper wing had a very low angle of attack (almost horizontal) as shown with yellow lines in the image below. The reason behind this would be to minimise drag (through minimal front area) while still getting reasonable downforce (as this increases with higher angles of attack). The upper wing was extended vertically on both sides, acting as endplates (see Total sticker), and it included a small Gurney flap (g) at the rear end, to delay airflow separation, thus increasing the wing efficiency.

Citroën Xsara T4 rear wing side view and dimensions – images by Manuel Madrid for Motor 16 and from Homologation Form

The car width was reduced to 1770 mm to fulfill the WRC regulations, making it more nervous (oversteering) while cornering. As with the kit car, the option of liquid cooling for front brakes and rear absorbers was included in the WRC.

The side mirrors were removed in the T4 and replaced by internal mirrors in order to reduce drag (due to the lower front area of the car). Some of the images included in this article confirm this solution, which was seen also in the Kit Car as well as in the WRC until 2002, when they all got back to the classic side mirrors.

However, the overlap with the Peugeot 206 WRC in the Championship almost kills the project, which was frozen by PSA. It was not until November’99 when the French Rally Federation (FFSA) created a new national homologation category, named France Rally Car (FRC), that the Xsara WRC project was given the green light again. The FRC category allowed cars with the same base of WRC to enter into the Championnat de France de Rallye, giving Citroën an alternative to regularly align the 4WD car while continuing with its development, in view of a future jump into the WRC. Thus, the car was homologated by the FFSA as a version of the Xsara VTS 1.8l 16v, through Hom. Form A-5612, Extension FRC.

Again, part of the WRC testing program was developed in Catalunya, in rally stages like Can Ferrer or the road traditionally used for the Pujada a les Ventoses, a hill climb race developed near Sant Jaume dels Domenys, as well as in France (Citroën private track at la Ferté Vidame and Saint-Michel des Portes).

P.Bugalski/J.P.Chiaroni, Citroën Xsara T4, Rallye Lyon-Charbonnières Rhône 2000, 1st – image by Xavier Pouchan

The T4 car took part in the 2000 French Rally Championship, winning in all the 7 events in which it participated, while the kit car was used as a benchmark for the 4WD car and participated in some European (ERC) events and many National Championships.

Citroën Xsara WRC

The development of the WRC continued in parallel to the participation of the T4 in France all over 2000. The efforts were concentrated mainly on gravel, as the car had been designed specifically for tarmac.

Then, in October Citroën launched the new version of the Xsara road car, with a new front design, easily identifiable by the larger headlights. That forced Citroën Sport to redesign the front of the WRC car. The changes affected the bonnet, wings, bumper, air intakes and splitter, and forced the relocation of some internal elements, for what the internal aerodynamics were also reviewed. The image below shows the main visible differences, such as the headlights or the removal of the front bumper side vents.

Citroën Xsara T4 (above) and WRC (below) – images by Manuel Madrid (above) and Petr Fitz (below)

Other improvements were implemented in the WRC car with respect to the T4, affecting, amongst others, the intercooler and the air intake systems. The car was finally homologated as a WRC version of the Xsara 2 VTS 2.0 16v (Hom. Form A-5626 Extension 01/01 WR) in March 2001, and only two days later the car was aligned in the Spanish Rally Costa Blanca Mediterràneo held in La Vila Joiosa, still as a T4, where Puras and Martí obtained an easy win.

Two weeks later, the debut in Catalunya shocked again the WR Championship: Puras/Martí lead after day one ahead of Bugalski/Chiaroni, who occupied the first position at the end of day two. Only mechanical issues (fuel pressure and clutch) prevented both teams from a well-deserved win, but the potential of the car on tarmac was clearly stated.

P.Bugalski/J.P.Chiaroni, Citroën Xsara WRC, Rally Catalunya 2001, 8th

To continue with the development on gravel, two cars were aligned in the Rally Acropolis, where both cars were equipped with air conditioning system, in spite of the extra weight (15kg). Bugalski/Chiaroni finished 6th and Radström/Thoner had to retire due to electrical issues.

On the next event, Sanremo, the team gave the first opportunity to drive the Xsara WRC car in the World Championship to the emerging duo Sebastién Loeb and Daniel Elena. And they responded with an excellent performance, fighting for the win till the last stage and finishing in an excellent second position.

C.Puras/M.Martí, Citroën Xsara WRC, Tour de Corse 2001, 1st – image by unknown

The first win of the Xsara WRC came in the next event, the Tour de Corse, and it was obtained by Puras/Martí. It would be the first of a long list that would extend to 2006.

The season 2002 represented for Citroën Sport the last year of preparation before assaulting the world titles in 2003. The plan was to take part in 8 events, discovering new surfaces such as Monte-Carlo, Safari or Finland. The season started with the same car used in 2001 and the incorporation of Loeb/Elena as regular drivers. And they could have won since their first appearance, in Monte-Carlo, if it was not by a tyre replacement carried out in a forbidden zone.

A new homologation was obtained on March 1st, 2002 (Extension 09/02 WR), with some modifications in the engine and the addition of new air intakes in the front bumper, as shown in the image below.

Citroën Xsara WRC front bumper in 2001 (above) and 2002 (below) – images by llluis555 (above) and Vít Bezděkovský (below)

Also, a new roof scoop was homologated, although it was not introduced until Rally Acropolis.

Citroën Xsara WRC roof scoop in 2001 (above) and 2002 (below) – images by Miquel Rovira (above) and Vít Bezděkovský (below)

The best result in 2002 arrived with the first win of Loeb/Elena at the Rallye Deutschland, as well as a third position in the gravel of Rally Safari by Radström/Giraudet, showing that the car was ready to attack a full World Championship in 2003, six years after it was conceived. It is probably the longest preparation a rally car has ever had, and the success in the coming years proves that it was a wise decision. Adding to this the incorporation of the World Champions Carlos Sainz (with Marc Martí as new codriver after the retrieval of Luis Moya) and Colin Mcrae (with Derek Ringer), the prospectives for Citroën Sport couldn’t be better.

However, in the constant search for improvement, an important modification arrived at the Xsara WRC in 2003: the introduction of the hydraulic anti-roll bars (as Variant Option), which we reviewed in a dedicated article, that was used since Monte-Carlo. Then, for Sweden, the team had to redesign the air intake system following problems with snow clogging the intake on the previous year’s event.

Wind tunnel evaluation of the Citroën Xsara WRC at the Soufflerie Climatique Ile de France, 2003

The aero development of the car continued during 2003. With this purpose, a full-scale unit was brought to the Wind Tunnel of the Soufflerie Climatique Ile de France (SCIdF), located at Saint Ouen l’Aumône, northwest of Paris. This facility, with airspeeds up to 230 km/h and a moving ground, was used for the evaluation of some external and internal improvements, such as the redesign of the front bumper or the introduction of five vertical strakes on the upper surface of the rear wing to improve downforce in high-speed corners when the car is sideways.

S.Loeb/D.Elena, Citroën Xsara WRC, Rally Catalunya 2003, 2nd

The new rear wing, together with changes to the turbo, intercooler and exhaust manifold, was part of the third evolution of the Xsara WRC, homologated in April (Extension 17/03 WR) and first used in competition in the Rally New Zealand 2003.

C.McRae/D.Ringer, Citroën Xsara WRC, Rally New Zealand 2003, ret. – picture by Citroën Sports

Following overheating issues in the Acropolis, the team improved the cooling system for Cyprus, while in Germany, the team worked on the ride height of the Xsara WRC. At the end of the season, Citroën won its first Manufacturer’s title, mostly thanks to the three wins obtained by Loeb/Elena (Monte-Carlo, Germany and Sanremo) plus the victory in Turkey by Sainz/Martí. The French/Monegasque duo ended in a brilliant second position in the Driver’s classification, beaten only by one point by Petter Solberg and Phil Mills (Subaru).

For 2004, Citroën decided to align just two cars, and the Scottish duo left the team. The next evolution of the car was homologated in April 2004 (Extension 28/04 WR) and first appeared in Rally New Zealand 2004. The main modification was the replacement of steel with composite material panels in the rear wing, thanks to the new regulations approved in March. Also, the minimum weight for the body shell, complete with roll-cage was changed to 320 kg, forcing the teams to review the car’s overall weight distribution. Another important modification was the addition of fans attached to the intercooler, to be used in the hottest events for better cooling of the turbo.

S.Loeb/D.Elena, Citroën Xsara WRC, Rally Cyprus 2004, 1st – picture by Petr Lusk – ewrc-result.com

Later, in June 2004, a new Variant Option was homologated, for the addition of fans for brake cooling, which were again modified in January 2005. At the end of the 2004 season, the results even improved those obtained in the previous year, as both Citroën and Loeb/Elena were crowned World Champions, after the six wins obtained by the French/Monegasque duo plus the win obtained by Sainz/Martí in Argentina. For Loeb/Elena it was the first of a long list of titles. For Sainz, it was the end of his rallying career, as the Spanish driver had decided to leave and to start his collaboration with VW in view of the Dakkar… although he soon came back, in 2005, to replace Duval in two events.

The new regulations for 2005 allowed the WRC cars longer than 4,2 m to increase the car width to 1800mm. Unfortunately, the Xsara didn’t reach such a length and had to remain with the original width of 1770 mm, which was a disadvantage in terms of cornering stability against the rivals. Also, the development of the car was almost complete, and only some modifications to the brake cooling system were introduced. As for the drivers, the absence of Sainz was covered with Duval/Smeets and Stohl/Minor.

F.Duval/S.Smeets, Citroën Xsara WRC, Rally Catalunya 2005, 2nd

Even without development, the car was still really efficient, allowing Loeb/Elena to obtain an impressive record of 10 wins (out of 16 events) to claim their second world title, while it was the third in a row for Citroën as a Manufacturer. But the efforts required to develop the new rally car, based on the C4, forced Citroën to withdraw from the Championship in 2006, while a private structure (Kronos Racing, led by Marc van Dalen) would be in charge of the Xsara WRC program.

In spite of this transfer to a private structure, Citroën made a final homologation of the car in April 2006 (extension 45/05 WR) that included a new design of the front bumper, with big side vents, as shown in the image below.

S.Loeb/D.Elena, Citroën Xsara WRC, Rally Finland 2006, 2nd – image by Petr Sagner

For the 2006 season, the Spanish duo Xevi Pons and Marc Julià joined the ‘official’ team, while Dani Sordo and Marc Martí drove a private Xsara inside the same Kronos structure. The eight wins obtained by Loeb/Elena seemed to be enough to ensure their third title, but an accident prevented them to participate in the last four events of the season. The final rush of Marcus Grönholm and Timo Rautiainen only served to put them one point behind Loeb/Elena, while Ford conquered the Manufacturers title for the first time since 1979.

S.Loeb/D.Elena, Citroën Xsara WRC, Rally Japan 2006, 1st – image by Dan Vrubel

The good results achieved by Pons/Julià (fourth position in four events) were overshadowed by the excellent results of Sordo/Martí during 2006, who finished second in Catalunya and Germany and third in Corsica and Sardinia. These results catapulted Sordo as an official Citroën driver, a role he still plays, fifteen years later, now in Hyundai. And proved the value of Marc Martí, as he co-drived Sainz, Puras and Sordo in the Xsara WRC with excellent results in all cases.

At the end of 2006, the Citroën Xsara kit car/WRC had obtained a total of 33 wins in events of the World Rally Championship, thus one of the most successful rally cars ever. And still, a 34th win could have arrived n 2007, when Duval/Pivato finished in the second position in Rallye Deutschland, only 20 seconds behind Loeb/Elena.

This post would not have been possible without the invaluable data and images provided by eWRC-RESULTS.com.

3 thoughts on “Aero evolution of the Citroën Xsara: from the Kit Car to the T4/WRC

  • 2022-01-04 at 23:13
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    Awesome article, pretty entertaining lecture awaiting for the 2022 season

    And better writing than any of the Dirtfish crappy articles

    Reply
    • 2022-01-05 at 10:56
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      David, you’re very kind with us. We will continue in 2022 doing as best as we can, as an amazing year has just started. Muchas gracias!!!

      Reply
    • 2022-01-06 at 02:30
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      Dirtfish has grown more sensationalist over the years, disappointing me because I know they’re much more competent than the persona they’re projecting now in order to appeal to ‘new fans’. They haven’t realized this is exactly why people are turning off their coverage of the main WRC season (their global rally coverage is still decent).

      Reply

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