Any production engine originally made by the manufacturer in question. Modifications to head and block are free, but must be based on standard parts, and engine power (rated at the flywheel) must be declared at the time of registration.
There are three power to weight classes (flywheel power on a Maha dyno listed in regulations, and weight including driver). The revised class structure for 2021 is as follows. Full regulations can be found via the sub-menu above.
Class A - 200bhp/tonne
Class B - 175bhp/tonne
Class C - 145bhp/tonne
Standard configuration and pick-up points must be used, dampers and springs are free. Electronically adjustable suspension is not permitted, nor should it be possible for for the driver to make any geometry changes whilst seated in the cockpit.
Class C must retain standard brake calipers, Classes A and B are free with the exception of carbon discs not being permitted.
4WD is not permitted, but cars may be front or rear-wheel-drive. Sequential gearboxes are not permitted (except for Clio Cup with additional ballast - see regulations), and Class C cars must run the standard production unit in its original location and orientation.
Any Motorsport UK List 1A, 1B or 1C tyre is permitted. Size is free, but tyres must be to MoT standards in all respects.
Hot Hatch typically features 14 rounds in a season - usually ‘double-headers’ either on one day, or spread over a weekend.
Club membership is just £25 for 12 months, season registration is £135, and double-header weekend entry fees (qualifying and 2 x 15min races) are typically between £280 and £360 depending on the circuit. Eligible cars can be built or bought from less than £4000.