The Mitsubishi HSR-II, known in Japan as the 三菱HSR-II (High Speed Research Vehicle II), was a concept car unveiled in Tokyo two years after the original HSR, as the second generation in Mitsubishi's series of high-performance research vehicles. Slightly larger than its predecessor, it was built in several fully driveable examples and gave a stronger impression of being a mid-engined design, even though its mechanical layout closely followed that of the new production Diamante (also sold as Sigma) and the HSX, later known as the 3000 GT. The HSR name stood for High Speed Research, reflecting a focus not only on high-speed stability but on the practical application of electronic systems, some of which had already migrated from the first HSR into Mitsubishi production models.
The car served as a testbed within a Multi Stage Improvement Programme drawing on expertise from across the Mitsubishi group, aiming to demonstrate technology that could bring greater comfort and safety to future buyers. At its core was a "thinking system" of seven computers mounted behind the two-seat cockpit, linked to sensors, cameras, and actuators to form the Overall Cybernetic Control System, or OCS-II, capable of drawing conclusions and making decisions in a manner resembling a reasoning process. OCS-II managed active functions such as drive-by-wire engine control, transmission shifting, four-wheel steering, electronic suspension, brake optimization, and the car's movable aerodynamic bodywork, alongside driver aids including automatic safe-distance monitoring and automatic parking assistance.
The HSR-II combined 4WD, 4WS, an electronically controlled independent suspension (4IS with ECS), and four-wheel ABS. Its Active ECS suspension countered body roll, squat, and dive in coordination with six aircraft-inspired aerodynamic flaps, including a movable front spoiler, extendable "duck bill" elements ahead of the front wheel arches, and rear brake flaps that also reduced rear lift, plus a venturi-effect underbody channel. With all aero devices retracted the drag coefficient was 0.20, rising to 0.40 under heavy braking with the flaps deployed; the flap configuration was inspired by the Control Configured Vehicle aircraft concept developed by Mitsubishi's aviation division.
Power came from a transversely mounted 2972 cc V6 with four overhead camshafts and 24 valves, based on the Diamante/3000 GT engine but fitted with twin small turbochargers, twin intercoolers, and a four-outlet exhaust, producing over 350 hp at 7000 rpm and 440 Nm between 2500 and 4500 rpm, compared with 225 hp and 275 Nm in the related 3000 GT road engine. Drive went through a four-speed automatic transmission with electronic control and a viscous coupling to all four wheels, running on purpose-made 245/50 R17 tyres rated to 300 km/h. The two-door coupe body used composite materials and featured a rear-hinged, front-lifting double-domed glass canopy alongside conventional side doors, with a futuristic cockpit including screens on the center console and passenger side and a flat-bottomed steering wheel. It measured 4800 mm long, 1950 mm wide, and 1165 mm high, with a 2720 mm wheelbase, 1650 mm track, and a weight of 1200 kg.
