14.5.4. Exhaust catalytic converters are required per Ch. 7 App. 8 Art. 1.8 except where a Vehicle does not require a catalytic converter in accordance with UK Government legislation.
14.5.5. Road Cars – Electrified Series Production: no modifications to the electrified propulsion system or powertrain are permitted.
14.6. Wheels and tyres
14.6.1. Except for Period Defined Vehicles( non-Rally) A-H inclusive tyres are to Ch. 8 App. 4 List 1A and List 1B.
14.7. Suspension and Steering
14.7.1. The suspension type mountings mounting method and position must remain the same as that fitted by the vehicle manufacturer with the exception of lever arm shocks which may be changed to Telescopic shock absorbers.
14.7.2. The shock absorbers may be of any make and may be uprated from standard. 14.7.3. Adjustable spring platform struts are permitted. 14.7.4. Springs are free but must retain their original location.
14.7.5. For Road Cars – Series Production bushes may be changed for similar polymer materials but not to spherical or similar metal joints.
14.7.6. For Road Cars – Specialist Production bushes may be changed for similar polymer materials spherical or similar metal joints.
14.7.7. Reciprocating ball steering may be replaced with rack and pinion.
14.8. Transmission
14.8.1. Road Cars – Series Production.
a.
b.
The gearbox and differential casing must be externally identifiable as that fitted to the original model or be a specified option and in either case remain in their original position;
The method of gear selection must remain standard( sequential selection only where fitted as standard).
14.8.2. Road Cars – Electrified Series Production, no modifications to the electrified propulsion system or powertrain are permitted.
15. Regulations for Modified Cars 15.1. Description
15.1.1. Modified Cars – Series Production: Must have been originally available through the normal commercial channels of the manufacturer in quantities of not less than 1000 Vehicles within 12 consecutive months.
15.1.2. Modified Cars – Electrified Series Production: Modified Electrified Saloons and Sports Cars in quantities of not less than 1000 per annum, compliant with Ch. 7 App. 11 Art. 1.10.
15.1.3. Modified Cars – Specialist Production: Must have been originally available in quantities of not less than 20 Chassis over a period of 12 consecutive months.
15.2. Vehicles produced in lesser quantities may be admitted subject to the manufacturer obtaining approval from ASN.
15.3. Safety
15.3.1. See Articles 2 – 12.
Motorsport UK National Competition Rules 2026 Edition 1
Chapter 14 Appendix 4- Technical Regulations 541