History Car 1980s

MG Metro 6R4

Overview Specs Highlights Characteristics

Overview

The Metro 6R4 shared a silhouette and brand with the Austin Metro road car, but not the road car's engine location or front-wheel-drive layout. Williams Grand Prix Engineering assisted Austin Rover in developing a bespoke Group B shell and driveline, combining mid-mounted engine mass with four-wheel drive and prominent aerodynamic add-ons. The badge stood for six cylinders, rallying and four-wheel drive.

Early test chassis did not use the final 3.0-litre V64V. The British Motor Museum's surviving 1983 chassis 001 prototype has a 2,646 cc V6 adapted from a cut-down Rover V8, rated 250 bhp for that particular test car. The eventual purpose-designed four-cam, 24-valve V64V was 2,991 cc; homologation Clubman examples were around 250 bhp, while the competition International configuration could reach about 410 bhp. A 2,646 cc figure must never be assigned to Tony Pond's 1985 RAC car.

FIA Group B form 277 took effect in November 1985. On the 1985 RAC Rally, Tony Pond/Rob Arthur finished third behind the two debuting Lancia Delta S4s, the 6R4's outstanding WRC result. British national rallies and rallycross continued to feature 6R4s, but the later categories and a 1986 Sanremo classification annulled by the FIA are not outright WRC victories.

Technical Specs & Innovations

  • FIA homologation: Austin MG Metro 6R4 Group B form 277, dated 2 November 1985 in FIA historic record
  • 1983 prototype distinction: Chassis 001 museum exhibit had a 2,646 cc, 250 bhp experimental Rover V8-derived six-cylinder engine
  • Full-series homologation engine: Purpose-built V64V 2,991 cc naturally aspirated 90° V6, separate from the prototype's hack-engine design
  • Valvetrain: Four overhead camshafts, four valves per cylinder, 24-valve heads
  • Engine position: Behind driver and co-driver, ahead of rear drivetrain; rear-mid-engine layout
  • Aspiration: Naturally aspirated competition V6; no turbocharger, supercharger or boost-based equivalence
  • Clubman road/homologation output: Approximately 250 bhp for road-linked 200-car homologation Clubman batch
  • International works output: Up to approximately 410 bhp in full Group B International trim, as described by the British Motor Museum
  • 1983 prototype power: 250 bhp for chassis 001; not identical in engine design to the 1985 Clubman car despite similar headline number
  • Engine developer: Austin Rover V64V design led by engineers including David Wood, rather than a production Metro engine
  • Drivetrain: Four-wheel drive with competition limited-slip components
  • Centre transfer: Ferguson Formula viscous-coupling epicyclic centre differential, per British Motor Museum technical narrative
  • Reference torque bias: British Motor Museum cites about 35% front / 65% rear split for the homologation works drivetrain
  • Gearbox: Five-speed competition transaxle/gearbox, manufacturer museum reference
  • Body construction: Steel spaceframe/strengthened shell with detachable wide-body panels, aerodynamics and roll-cage protection
  • Shell relationship: Competition Metro-shape panels, not the mass-market front-engine/front-wheel-drive production monocoque
  • Suspension: Long-travel independent competition suspension designed for gravel and tarmac setup variation
  • Wheelbase development: Prototype front/rear aero, track and wheelbase underwent changes before the full homologation spec
  • Competition brake layout: Four-wheel competition disc brakes with different dimensions/calipers and cooling changes through FIA extensions
  • Homologation batch: British Motor Museum records 200 Clubman examples built; 250 bhp is the museum's Clubman nominal output
  • Prototype size: Chassis 001 measured 3,340 mm long in museum inventory; not a universal final-series competition-body length
  • 1985 Clubman length: 3,350 mm in the British Motor Museum's Clubman collection reference
  • Museum Clubman engine: 2,991 cc and 250 bhp; separate from the 410 bhp purpose-tuned International rally car
  • Fuel and safety: Group B safety fuel cell, roll cage, extinguishing equipment and two-person rally crew
  • 1986 extension record: FIA form 277 lists changes to suspension, steering, final drive, brakes and gearbox during 1986
  • Event-specific configuration: Suspension, gearbox, brakes and protective guards varied by works rally versus private sprint/rallycross use
  • Post-Group B use: National rallying, rallycross and modified cars after 1986 have different regulations and can have non-period engines

🏆 Competitive Highlights

  • 1984 public development: Austin Rover and Williams presented the MG Metro 6R4 project to the press, using interim prototype engines for testing.
  • Early 1985 national debut successes: Tony Pond's prototype competed in domestic rally events, including an early Gwynedd Rally overall win, before FIA homologation.
  • November 1985 Group B homologation: The full 2,991 cc 6R4 became eligible under FIA form 277.
  • 1985 RAC Rally: Tony Pond and Rob Arthur finished third outright, behind Toivonen/Wilson and Alén/Kivimäki in Lancia Delta S4s.
  • 1986 Monte Carlo Rally: Pond/Arthur retired following an accident; Malcolm Wilson/Nigel Harris suffered a transmission retirement.
  • 1986 Tour de Corse: Pond/Arthur and other 6R4 entries retired with camshaft, engine and oil-system problems.
  • 1986 1000 Lakes Rally: Per Eklund/Dave Whitlock finished seventh, Harri Toivonen/Cedric Wrede eighth and Wilson/Harris tenth in 6R4s.
  • 1986 Sanremo result warning: Malcolm Wilson/Nigel Harris were provisionally classified fourth, but the whole rally result was annulled by the FIA and does not award valid WRC points.
  • 1986 RAC Rally: Pond/Arthur finished sixth; other 6R4 crews also reached the finish, while reliability problems caused several retirements.
  • World-championship record: No outright WRC rally victory or WRC world championship title was achieved by the 6R4 during Group B.
  • 1987 onwards: 6R4 cars remained in British and other domestic rally/rallycross competition under successor rules, not as eligible Group B WRC factory cars.

Driving Characteristics

The absence of a turbocharger removed a key source of forced-induction response delay, allowing the V64V's torque response to follow throttle input relatively directly. The tradeoff was that an unsupercharged V6 could not match all contemporary turbo rivals' peak engine output on a given capacity/weight basis.

Short overall dimensions and a rear-mid engine aided rotation but also demanded careful braking balance and suspension setup at high speed. The museum's 35:65 axle torque distribution illustrates the concept's rear-biased traction; full stage behaviour depended on differential calibration and tyre choice.

Mechanical reliability—not just theoretical agility—shaped the 6R4's WRC results. Multiple 1986 mechanical retirements make the RAC third a representative high point rather than proof of all-rally dominance.

Development & legacy

The 6R4 represents Britain's unusual naturally aspirated alternative to the twincharged/turbocharged Group B field. Its prototype, homologation Clubman and International rally specifications each deserve separate treatment; subsequent rallycross success must not be counted as a 1980s outright WRC title.

Research sources & verification

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