WRC Technical Regulations and Car Homologation terms

2021 Regulations

As approved by FIA World Motor Sport Council on December 16th, 2020

Appendix J 2021 – Article 255A – Specific regulations for WRC – published on 16.12.2020

WRC Sporting Regulations 2021 – update 16.12.2020 – published on 18.12.2020


Previous seasons

2020 Regulations

As approved by FIA World Motor Sport Council on December 4th, 2019

Appendix J 2020 – Article 255A – Specific regulations for WRC (published on 12.12.2019)

2019 Regulations

As approved by FIA World Motor Sport Council on October 12th, 2018:

As part of an overall cost reduction plan aimed at removing or reducing the cost of elements that do not add to the spectacle of the Championship, the number of test days will be reduced from 55 to 42 for WRC Manufacturer teams (on calendar year).

Appendix J 2019 – Article 255A – Specific regulations for WRC (published on 17.06.2019)

2018 Regulations

No major changes over 2017 regulations.

Appendix J 2018 – Article 255A – Specific regulations for WRC (corrected on 14.02.2018)

2017 Regulations

As approved by the World Motor Sport Council in Mexico City, Jul. 10th, 2015, and subsequent modifications.

Main modifications allowed, with respect to 2016.

  1. Bigger car size: car width is increased up to 55 mm.
  2. Lighter cars: minimum car weight is reduced to 1190 kg (from previous 1200 kg).
  3. More powerful cars: increase of turbo air restrictor diameter from 33 to 36 mm is allowed. This means an important increase in power (estimated at an additional 60-80 hp) at higher revs. Limit of pressure in the inlet manifold remains fixed at 2.5 bar, so torque should not change significantly.
  4. Better traction: use of active center differential allowed.
  5. Better brake capacity: use of 370 mm brake discs is allowed, exclusively for tarmac stages. For loose surfaces, maximum remains at 300 mm.

These new regulations have been designed on the basis of a three-year homologation cycle. Each team can use up to three jokers per season to introduce technical modifications to the car (including development, power increase, durability or aerodynamics).

Greater freedom to be afforded with the aerodynamics, setting this World Rally Car aside from many of its recent predecessors. These are the main modifications affecting the aerodynamics of the new cars.

  1. Front bumper: it can protrude 60 mm more. Composite materials are now allowed, which should help in minimizing damages on rough terrains.
  2. Rear spoiler/wing: it can be 50mm higher and 55mm wider, but the profile is fixed.
    It can overhang the car body by 50 mm (30mm longer than in 2016). No vertical fins allowed in the central part of the upper wing, only on both sides (minimal separation 1m).
  3. Rear diffuser: maximum permitted dimensions, free shape, and it can protrude up to 50mm from the rear bumper.
  4. New openings are allowed on the front and rear fenders.

Appendix J 2017 – Article 255A – Specific regulations for WRC (published on 06.01.2017)

Homologation extension form 400/01 WRC (not public)

2017 WRC Sporting Regulations and Appendices (published on 28.06.2017)

Other FIA Regulations related to WRC

2013-2016 Regulations

Aerodynamic devices
The rear aerodynamic device must be entirely contained within the frontal projection of the car without its rear-view mirrors. Max width is 1820 mm.

Manufacturers can only homologate one aerodynamic package per year and this cannot evolve throughout the rest of the year.

Appendix J 2016 – Article 255A – Specific regulations for WRC cars (published on 16.12.2015)


All current WRC car generation were homologated by FIA in December 2016, so that homologation was valid since January 1st, 2017. The homologation of the Variant kit WRC 2017 is known as 400/01 for all cars, and it is valid till the end of the year 2024.

Once the cars were homologated, the Appendix J of the Article 255 set which parts of the car require homologation and which are free of homologation. Regarding the main parts of the aero package, the parts requiring homologation when modified versus the original part included in 400/01 are:

1. Body openings, which are only allowed for the cooling of:

‐ engine, transmission
‐ brakes
‐ power steering
‐ electric/electronic equipment
‐ cockpit/ driver
‐ air conditioning system
‐ power assisted gearshift system
‐ shock absorber
‐ hubcarriers

2. Roof panel and roof vents (VO)

3. Engine bonnet

4. Boot lid

5. Fenders, air inlet/outlet and louvres (VO)

6. Door and door sills

7. Front bumper and lower (removable) part, although air ducts and mountings are excluded

8. Rear bumper, openings and louvres (VO), although wheel visibility and mountings are excluded

9. Rear diffuser and rear protection

10. Rear wing, Trailing edge / Angle bracket (gurney flap), secondary profile and wing position

11. Front and rear wheel arches and housings

VO means variant option, affecting to parts that have to be homologated but do not require the use of a joker.

On the contrary, those parts impacting on car aerodynamics whose homologation is not required and can be freely replaced are:

1. Rear mirrors

2. Underbody protections

3. Front bumper air ducts and mountings

4. Rear bumper wheel visibility and mountings

There are different types of homologations:

ER – Erratum: replaces and cancels an incorrect piece of information previously
supplied by the constructor on a form.

ERJ – Erratum joker: counted for each article modified.

VO – variant option (supplied on specific request).

VK – variant kit (supplied on specific request).

VF – variant supply: two suppliers providing the same part for the manufacturer and the client does not have the possibility of choice.

VP – production variant (supplied on request and available from dealers).

ET – evolution type: modifications made on a permanent basis to the basic
model (complete cessation of the production of the car in its original

Use of variants: the competitor may use any variant or any article of a variant as he
wishes, only on condition that all the technical data of the vehicle, so designed, conforms to that described on the homologation form applicable to the car, or expressly allowed by Appendix J.

Each homologation is identified by the combination of two numbers: 4XX / YY

4XX meaning the total number of homologation, starting from 400

YY is the number of homologations of the type (ER, VO,…)

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