The 721 was the successor to the March 711, which had delivered a strong 1971 campaign and raised hopes of a genuine championship challenge. March entered 1972 intending to leap to the front of the Formula One grid, but the programme quickly fractured into multiple design directions. The basic 721 was essentially a mild evolution of the 711, built for customer teams including Frank Williams Racing Cars and Günther Hennerici's Eifelland operation. The Eifelland car received distinctive new bodywork by designer Luigi Colani and was raced as the Eifelland E21.
The centrepiece of March's 1972 programme was the 721X, a completely new design by Robin Herd. Herd sought to concentrate the car's mass at its centre, reducing the moment of inertia for improved agility. To achieve this he mounted a transversal Alfa Romeo gearbox between the Cosworth DFV engine and the rear axle — an unconventional layout intended to shorten the mechanical package. The suspension geometry employed highly angled rear springs operated through levers and pullrods.
In practice the 721X proved a failure. The Goodyear tyres March used in 1972 were fundamentally incompatible with the chassis, placing excessive load on the front tyres and producing a car that alternated between oversteer and understeer without ever settling. Factory driver Niki Lauda, who had joined March on the strength of the 711's promise, called the 721X "a complete failure", "a stillbirth", and "a debacle". The car offered its drivers no confidence and no lap time.
Faced with an uncompetitive 721X and a season collapsing around them, March took drastic action. In just nine days the team constructed the 721G, adapting a conventional Formula Two chassis — the March 722 — for Formula One use. Suspension and brakes were carried over from the customer 721, and the Cosworth DFV was once again the engine. The G-Type was a pragmatic, unpretentious machine that at least allowed the drivers to race competitively.
Ronnie Peterson, driving the 721G, took a third-place finish at the German Grand Prix, providing the season's high point for the March works team. Niki Lauda, despite spending the entire year wrestling with the 721X's problems, finished the season without a championship point. The fact that March had designed and fielded three distinct Formula One cars within a single year underlined both the team's resourcefulness and the severity of the 721X miscalculation.
The March 721 season stands as a cautionary chapter in the team's history. The conceptual ambition of the 721X — particularly its mass-centralisation philosophy and transversal gearbox — was not without logic, but the combination of tyre incompatibility and limited development time rendered it unraceable. The 721G rescue operation demonstrated that rapid, pragmatic engineering could salvage points where sophisticated theory had failed. March would rebuild in subsequent seasons, but the 1972 campaign remained a reminder that innovation without a reliable development loop could undermine even the most promising programmes.