Bruce McLaren had been a factory driver for Cooper but grew dissatisfied as the team's competitiveness declined through the mid-1960s. In 1965 he recruited Robin Herd — an aerospace engineer with experience on the Concorde project at the National Gas Turbine Establishment — to design a Formula One car for the new 3.0-litre formula coming into force in 1966. The M2A development car was completed in September 1965 powered by a 4.5-litre Oldsmobile V8, used to validate Herd's design concepts and test Firestone tyres. McLaren, still under contract to Cooper, initially claimed the M2A was a pure tyre test bed. Construction of at least two M2B chassis began at the team's Colnbrook factory, with Gordon Coppuck — later to become McLaren's chief designer — joining the team in December 1965.
The M2B was a mid-engined monocoque, built at a time when monocoque construction had been popularised by the Lotus 25. Herd employed Mallite — a composite of balsa wood bonded between two aluminium alloy sheets, originally developed for aircraft interior panelling — in the chassis construction. The material was exceptionally stiff, giving the M2B torsional rigidity of nearly 10,000 lb·ft per degree, a record for open-cockpit racing cars at the time. However, Mallite was difficult to form into curves and complicated to repair after crash damage, so it was used only for the inner and upper skins on the race car, with aluminium alloy elsewhere.
Herd's aeronautical background also led the team to experiment with a rear wing generating downforce on the M2A — tested at Zandvoort in November 1965, cutting lap times by three seconds, more than two years before wings appeared in Grands Prix. Engine difficulties ultimately prevented the wing from being used on the M2B in racing.
Engine selection was a critical problem for 1966. With the capacity limit doubling to 3.0 litres and no team having a suitable unit ready, McLaren chose to use a modified Ford Indy V8. The DOHC engine, which had won the 1965 Indianapolis 500 with Team Lotus, was reduced from 4.2 litres to 3.0 litres by a third-party contractor and called the Ford 406. It produced approximately 300 bhp in a narrow power band and was heavy, with the combined engine-gearbox package weighing nearly as much as a rival Brabham's entire car. For races where the Ford was unavailable or problematic, a Serenissima M166 3.0-litre V8 producing around 260 bhp was substituted, requiring modifications to the monocoque.
The M2B made its race debut at Monaco, where McLaren qualified tenth and ran as high as sixth before retiring with an oil leak after nine laps. The Serenissima engine was introduced at Belgium but suffered terminal bearing failure in practice, leaving McLaren unable to start. The team missed the French Grand Prix entirely.
At the British Grand Prix at Brands Hatch the M2B finished sixth, scoring McLaren's first championship point. A further non-start followed at the Dutch Grand Prix when the Serenissima failed again. The German and Italian races were skipped in anticipation of an improved Ford unit. At the United States Grand Prix McLaren drove to fifth place, earning two more points. The Mexican finale ended with another engine retirement.
The car had been planned to run in a New Zealand green livery, but a sponsorship arrangement with the makers of the film Grand Prix resulted in it being painted white with a green stripe to represent the fictional Japanese "Yamura" team. A second car for Chris Amon was intended but never materialised due to engine availability.
The M2B scored three points from six race entries — an unspectacular result that nonetheless established McLaren as a constructor and demonstrated the team's capacity to compete at the top level of the sport. Robin Herd reflected later that the design emphasis on the elegance of the chassis structure had taken precedence over outright speed, and that the Ford engine choice proved decisive in limiting the car's potential. Teddy Mayer, who would later manage the organisation, agreed that the engine was the central problem.
The M2A development car was sold into private hands in the United Kingdom and destroyed by fire in 1969. Three M2B chassis were similarly sold on; one remained awaiting restoration in the United States, and another was on display at the Donington Grand Prix Exhibition. The McLaren team's subsequent cars adopted conventional aluminium construction, and neither the Mallite material nor the Ford or Serenissima engines were used again. Not until the Cosworth DFV became available in 1968 did McLaren win a Formula One race, with the M7A.