The 787 was an evolution of Mazda's 767 and 767B designs from 1988 and 1989. Designer Nigel Stroud carried over many mechanical elements from the 767 but made significant changes, most notably replacing the 767's 13J Wankel engine with the purpose-built R26B. This new four-rotor unit shared a similar layout and displacement to its predecessor but incorporated more granular variable intakes, three spark plugs per rotor instead of two, ceramic apex seals, and variable-length trumpets. At full output the R26B produced around 900 hp at 10,000 rpm, though it was typically restricted during racing.
The radiator layout was also revised: where the 767 carried radiators beside the cockpit, the 787 integrated a single radiator into the nose, with air ducted under the bodywork and exited in front of the windshield. A Gurney flap at the exit aided front-end downforce. The monocoque was constructed from carbon and Kevlar by Advanced Composite Technology in the United Kingdom. Two 787 chassis were built for 1990.
For 1991 Mazda developed an improved variant, the 787B. Key upgrades included a continuously variable telescopic intake system for the R26B, replacing the earlier stepped-variable arrangement, which raised torque to 608 N⋅m at 6,500 rpm. The engineers also revised suspension geometry to accommodate larger wheels and carbon ceramic brakes. To prioritize reliability and fuel efficiency, the redline was restricted to 8,500 rpm, limiting power to around 650 hp. Former Le Mans winner Jacky Ickx was retained as an advisor. Three new 787Bs were built for 1991.
The first 787 chassis debuted in April 1990 at the Inter Challenge Fuji 1000 km in the All Japan Sports Prototype Championship. For Le Mans that year, Mazdaspeed entered two 787s alongside an older 767B. Ickx was hired to prepare the cars, with driver lineups including Stefan Johansson, David Kennedy, and Pierre Dieudonné in one car, and Bertrand Gachot, Volker Weidler, and Johnny Herbert in the other. Both 787s qualified in the mid-twenties and ran reliably before mechanical failures — an oil leak and a subsequent electrical fire — ended their races in the early hours of Sunday morning. The 767B survived to finish twentieth.
In the remainder of the JSPC season, the 787s recorded a mix of mid-field results, with Mazda finishing fourth in the constructors' standings.
For 1991, FISA reclassified cars using non-Formula One-spec 3.5-litre engines, including the Mazda, into the C2 class. The French Oreca team took charge of the world championship campaign. Jacky Ickx and Oreca persuaded FISA to allow the 787s to run at 830 kg rather than the 1,000 kg standard for C2, citing the rotary engine's characteristics.
At the 59th 24 Hours of Le Mans, Mazdaspeed entered three cars: one older 787 (car number 56) and two brand-new 787Bs (numbers 18 and 55). The No. 55 car, driven by Weidler, Herbert, and Gachot, carried a distinctive bright orange and green livery in honour of Japanese clothing sponsor Renown rather than the usual white-and-blue colours.
Team manager Ohashi elected to run the No. 55 car on an aggressive strategy, trusting in the fuel economy and reliability demonstrated at pre-race tests. In the race's early stages No. 55 moved into the top three, benefiting as Mercedes-Benz machinery encountered gearbox and mechanical problems. At the 22nd hour, the car took the outright lead after the leading Mercedes was forced to pit. Johnny Herbert drove the final stint, bringing the 787B across the line first after completing 362 laps and covering 4,932.2 km — records for the then-recently modified circuit layout.
The other two Mazda entries finished sixth and eighth. The victory marked the first Le Mans win by a Japanese manufacturer and, as of 2026, remains the only win by a car using a rotary rather than reciprocating engine.
The 787B's R26B engine displaces 654 cm³ per rotor across four rotors, for a total equivalent swept volume of 2,616 cm³, though it is typically cited in class regulations as 2,622 cm³. At Le Mans specification, the engine produced approximately 700 hp at 9,000 rpm and 608 N⋅m of torque at 6,500 rpm. The carbon-Kevlar monocoque weighed approximately 850 kg in race trim, with 18-inch Volk Racing magnesium alloy wheels and carbon disc brakes. A five-speed Porsche-manufactured gearbox was retained from the 767 lineage.
Following the 1991 season, FISA mandated 3.5-litre reciprocating engines for the top class, effectively ending Mazda's Group C program. The R26B engine was subsequently used in the RX-792P in IMSA GTP competition and in a modified WR chassis at Le Mans 2002 by Autoexe Motorsport.
The winning No. 55 787B is preserved at the Mazda Museum in Hiroshima, with a replica on display at the Le Mans Museum. The car appeared in numerous video games, including the Gran Turismo series, Forza Motorsport, and Assetto Corsa. Winning driver Herbert went on to a Formula One career with three race victories. Gachot famously gave up his Jordan seat at the 1991 Belgian Grand Prix — where he was replaced by Michael Schumacher for his debut — after receiving a prison sentence for a CS gas attack on a London taxi driver. Weidler retired from racing after being diagnosed with tinnitus.
The 787B is regarded as one of the most iconic Japanese racing cars ever built and a landmark in Wankel rotary engine history.