The Ford-powered M2B made its debut driven by McLaren at the world championship season-opening . There he qualified 10th on the grid and ran as high as sixth but retired after nine laps due to an oil leak. After Monaco McLaren decided "it looks as though we're going to have to make some fairly drastic moves in the engine room", and so for the next race in Belgium the Serenissima engine was used. The replacement unit did not provide an immediate solution though, terminally damaging its bearings in practice. With no spare, McLaren was unable to start the race. The team missed the next race in France, but at the at Brands Hatch the M2B finished sixth to score McLaren's first championship point. Another non-start resulted when the Serenissima failed again before the , and the entries for the German and Italian Grands Prix were withdrawn in anticipation of the improved Ford engine being readied. Thus equipped at the , McLaren drove to fifth place and two more points. At final event in Mexico, the rear bodywork was cut away to help prevent overheating but the engine failed during the race. McLaren had intended for Chris Amon, who was already racing sports cars for the team, to race a second car but the engine problems prevented this.