March 721X car-by-car histories

A restored March 721X at the Tjolöholm Classic Motor in May 2012. Licenced by Flickr user 'nakhon100' under Creative Commons licence Attribution 2.0 Generic (CC BY 2.0). Original image has been cropped.

Robin Herd’s 1972 F1 design was the March 721X, with an Alfa Romeo gearbox positioned in front of the engine to concentrate the car’s mass closer to its centre of rotation. It was quickly abandoned.

After March had won its first Grand Prix with the orthodox March 701, and Ronnie Peterson had then finished second in the drivers’ championship and March third-equal in the constructors' title in 1971, designer Robin Herd intended March to win the championship in 1972. The team started the season with uprated March 711s renamed March 721s, while Herd finalised his 721X design. This used the same monocoque as the successful 711, but had redesigned side radiators, a bluff nose, inboard rear suspension using a pushrod arrangement, substantial rollhoop supports, and a completely revised transmission that used Alfa Romeo gearbox components. This positioned the gearbox in front of the final drive, concentrating the car’s mass around the centre and briefly popularising the expression “low polar moment of inertia”. The idea came from the Alfa Romeo T33 sports car which Ronnie Peterson had raced at Watkins Glen in 1971, but the same approach had been used on the Porsche 908/3 as well. It should, in theory, have improved cornering. However, Goodyear’s tyres were not suited to the design, and the result was understeer on the way into a corner and vicious oversteer on the way out.

The car was ready for the Race of Champions in mid-March 1972, where Peterson complained of heavy steering and understeer, but was confident the car would work. At the Spanish Grand Prix, Niki Lauda drove 721X/1 and Peterson had a brand new 721X/2, but the oversteer problems were still in evidence. Lauda hated the car, but kept his thoughts to himself. Both cars retired at Jarama and finished well down the field in wet conditions at Monaco. For the Belgian GP in early June, Peterson’s car had been modified with orthodox 711/721 rear suspension and the Alfa Romeo gearbox had been replaced by a Hewland FG400. Lauda’s car had the Alfa Romeo gearbox mated to a Powr-Lok differential. Neither combination worked, and the 721Xs were retired, to be replaced by March 721Gs.

It is a pity that one of the most talented Formula 1 designers of his generation would not get another chance to build another F1 car aimed at winning the title. Financial limitations would mean that all future March F1 cars would be based on the company’s successful F2 cars.

Both 721Xs were acquired from March by a dealer, but a dispute with the factory meant it was 1978 before he actually took delivery. One went to the Ronnie Peterson museum in Sweden, before moving to Germany, and the other passed through the hands of a few British dealers, collectors and restorers before being sold to Sweden. Both are runners. The German-owned car has appeared at the AvD-Oldtimer-Grand-Prix and the Swedish-owned car has appeared at the Goodwood Festival of Speed.

Please contact Allen Brown (allen@oldracingcars.com) if you can add anything to our understanding of these cars.

These histories were last updated on 08 Jun 2026.