World Rally Car

World Rally Car is a racing automobile built to the specification set by the FIA, the international motorsports governing body and compete in the outright class of the World Rally Championship (WRC). The WRC specifications were introduced by the FIA in 1997.^[1]

Regulations

1997–2010

A Subaru Impreza WRC2006 being prepared by Prodrive

Between 1997 and 2010, the regulations mandated that World Rally Cars must have been built upon a production car with a minimum production run of 2500 units. A number of modifications could be made including increasing the engine displacement up to 2.0L, forced induction (including an anti-lag system), addition of four wheel drive, fitment of a sequential gearbox, aerodynamic body modifications, weight reduction to a minimum of 1230 kg and chassis strengthening for greater rigidity.

Unlike the requirements for the preceding Group A cars, manufacturers were no longer required to build "homologation specials" in order to meet approval. The base model did not need to have all the characteristics of the WRC car, as evidenced from cars such the Peugeot 206, 307, Citroën Xsara and Škoda Fabia, which during this period had no road car variant with a turbocharged petrol engine or four wheel drive.

To limit power, all forced induction cars were fitted with a 34 mm diameter air restrictor before the turbocharger inlet, limiting the air flow to about 10 cubic meters per minute. The restriction was intended to limit power output to 300 hp although some WRC engines were believed to produce around 330–340 hp. Engine development did not focus on peak power output but towards producing a very wide powerband (or power curve). Typically, power output in excess of 300 hp was available from 3000 rpm to the 7500 rpm maximum, with a peak of 330–340 hp at around 5500 rpm. At 2000 rpm (the engine idle speed in "stage" mode) power output was slightly above 200 hp.^[2]

2011–2016

Starting in 2011, rules for WRC cars have changed to be more restrictive. Now the regulations are derived from the ones for S2000 cars, with a different engine and an aerodynamic kit. The cars are smaller models (there is no longer a minimum 4m length), with a 1600 cm³ direct injection turbo engine with a 33 mm diameter air restrictor and a maximum pressure of 2.5 bar absolute (this will limit torque to about 400 N.m or less^[3]).

Exotic materials (titanium, magnesium, ceramics and composite) are forbidden except when present in the base model. Carbon fibre and aramid fibre are very restricted ("only one layer of fabric is used and is affixed to the visible face of the part"), except for bodywork's side protections where multiple layers of aramid fibre are allowed.

The gear changes must be made with a mechanical system, so the paddle shifters are not allowed. However the system was re-allowed in 2015. There is no center differential (earlier it used to be 3 differentials, with a center/3rd differential included), but the new regulation allows only front and rear axle differential (eliminating the center differential to reduce cost), and they must be mechanical, without electronic control or hydraulic or viscous systems (from 2006 to 2010 the center differential and previously all 3 could be active^[4]). Minimum weight is 1200 kg empty and 1350 kg with driver and co-driver (in both cases with only one spare wheel).^[5]

2017

1600 cm³ turbocharged engine will be retained in upcoming 2017 World Rally Car regulations, but the turbo restrictor diameter will be increased from 33 mm to 36 mm, and remain at 2.5 bar of maximum pressure. Minimum weight will be decreased by 25 kg.

Manufacturers are also given more freedom to maximise aerodynamic performance.

Cars

Citroën Xsara WRC Citroën C4 WRC Citroën DS3 WRC Ford Escort WRC Ford Focus RS WRC Ford Fiesta RS WRC Hyundai Accent WRC Hyundai i20 WRC Mini John Cooper Works WRC Mitsubishi Lancer WRC Peugeot 206 WRC Peugeot 307 WRC SEAT Córdoba WRC Škoda Fabia WRC Subaru Impreza WRC Suzuki SX4 WRC Toyota Corolla WRC Volkswagen Polo R WRC

Manufacturer	Car	From	To
Citroën	Xsara WRC	2001	2006
	C4 WRC	2007	2010
	DS3 WRC	2011	2016
	C3 WRC	2017	-
/ Ford	Escort WRC	1997	1998
	Focus RS WRC	1999	2010
	Fiesta RS WRC	2011	-
/ Hyundai	Accent WRC	2000	2003
	i20 WRC	2014	-
MINI	John Cooper Works WRC	2011	2012
Mitsubishi	Lancer Evolution WRC	2001	2002
	Lancer WRC	2004	2005
Peugeot	206 WRC	1999	2003
	307 WRC	2004	2005
SEAT	Córdoba WRC	1998	2000
Škoda	Octavia WRC	1999	2003
	Fabia WRC	2003	2005
Subaru	Impreza WRC	1997	2008
Suzuki	SX4 WRC	2007	2008
Toyota	Corolla WRC	1997	1999
	Yaris WRC	2017	-
Volkswagen	Polo R WRC	2013	-

References

1. "WRC History". Suzuki Sport.
2. "Subaru Rally Engine – Developing a World Rally Car power plant", page 23-30, Race Engine Technology, issue 005, 2004
3. For instance, officially the Citroën DS3 WRC has 350 N·m (35.7 kgf·m) at 3,250rpm.
4. "Rally of Turkey 2010 – Glossary". Retrieved 2011-02-21.
5. http://argent.fia.com/web/fia-public.nsf/92B8777DD7239078C1257802003B3157/$FILE/255A_2011.pdf

External links

• The cars at WRC.com