Although it has a family resemblance with the MS80 with which Matra won the 1969 Constructors' Championship, it is a completely different car with a steel tube chassis instead of an aluminium monocoque.

At the back the engine is mounted back-to-front with the gearbox and transfer case directly behind the driver.

The Ferguson transmission and other necessary additions left the car much heavier than the two-wheel drive MS80s (635 kg with no fuel).

Like the Lotus 63, the MS84 made its first appearance at the Dutch Grand Prix, where Jackie Stewart tried the car out but opted to use his MS80, as he would for the rest of the season.

The car was still present at all the remaining races as a spare, and at Silverstone Jean-Pierre Beltoise gave the car its first race and came home ninth, six laps behind Stewart's two-wheel drive Matra (but three laps ahead of John Miles's Lotus 63).