The Benetton Group had spent several years sponsoring Formula One teams, including Alfa Romeo and Tyrrell, before backing Toleman from 1983. When Benetton bought Toleman outright in late 1985, the existing team structure was retained largely intact. Peter Collins continued as team manager and Rory Byrne remained as chief engineer. The chassis that had been in development as the Toleman TG186 was simply renamed the Benetton B186. The team remained based at its headquarters in Witney, England.
The deal to acquire BMW turbocharged engines replaced the privateer Hart 415T units that had powered Toleman since 1981. BMW's primary focus for 1986 was the new "lay-down" version of the M12/13, designed for the radical low-line Brabham BT55; the standard upright version was supplied to Benetton and to Arrows. The B186 also ran on Pirelli tyres, at a time when most front-running teams used Goodyear rubber.
The deal between Benetton and Toleman was finalised only in October 1985, leaving Byrne just weeks to begin designing the B186 before the first race of 1986 in Brazil. Three chassis were completed in time for the opening round; four more were built during the season. All seven raced at various points, though chassis number 4 was destroyed in a practice accident at the Canadian Grand Prix when Teo Fabi crashed. The monocoque was constructed from carbon fibre, by then standard practice in Formula One.
A distinctive design challenge was accommodating the team's two drivers, whose physical sizes differed considerably: Fabi stood approximately 1.68 metres tall while Berger was 1.83 metres. The car's livery reflected Benetton Group ownership, featuring the company's characteristic multi-coloured streaks on a white background on the engine cover, alongside sponsor logos. At the Detroit Grand Prix, both cars ran with multi-coloured tyre sidewalls.
The BMW M12/13 engine in B186 specification produced approximately 50 bhp more than the official factory units supplied to Brabham, made possible through modified engine management chips — a discrepancy that drew scrutiny from BMW's engine chief Paul Rosche at the Austrian Grand Prix. The B186s were consistently among the fastest cars through speed traps. At Monza, Berger was clocked at 351.22 km/h in qualifying, the second-highest speed recorded during the original turbo era, exceeded only by Nelson Piquet's Williams-Honda at 352.135 km/h at the same circuit the following year.
Despite the raw power, the first half of the season was complicated by the BMW engine's abrupt, light-switch power delivery, which made the chassis difficult to handle. The Pirelli tyre partnership also yielded inconsistent results early on, as the Italian manufacturer had less pre-season testing data than Goodyear users. Mid-season development addressed both problems: aerodynamic updates to the front and rear wings, underbody, and suspension, plus a stronger chassis and revised setup concepts, significantly improved the car's competitiveness and reliability.
The B186 was at its strongest on the high-speed "power circuits" — Imola, Spa-Francorchamps, Hockenheim, Monza, and the Österreichring. At the Austrian Grand Prix, the Benettons were demonstrably faster than Williams, McLaren, and Lotus, and were on course for a dominant one-two finish before Fabi over-revved his engine on a kerb and Berger's battery failed, costing him five laps in the pits. Despite nineteen retirements from 32 starts across the season, the car scored two pole positions and three fastest laps.
Berger's win at the 1986 Mexican Grand Prix came through tyre strategy. The relative durability of the Pirelli compounds allowed Berger to complete the race without a pitstop for fresh tyres, while rivals Nelson Piquet, Alain Prost, and Nigel Mansell all made at least two stops or suffered mechanical issues. The victory was Benetton's first as a constructor and Berger's first of a career that would ultimately yield ten wins. It also proved to be the final Grand Prix victory for the BMW M12/13 engine.
Benetton comfortably outperformed fellow BMW-powered teams Brabham and Arrows throughout the season, despite BMW and Pirelli having expected the innovative Brabham BT55 to be their fastest customer. For the 1987 season the B186 was replaced by the B187, powered by a Ford turbo unit.
The B186, alongside other BMW-engined cars of the 1983–1986 period, is among the most powerful Formula One cars ever constructed. Its 1986 season established Benetton as a credible constructor rather than merely a sponsor, and validated the decision to purchase Toleman. Known surviving chassis include number 2, on display at Mondello Park in Ireland, and number 6, at the BMW Museum in Munich.