A Mark Wild and staff designed 1074 cc water-cooled four-cylinder engine with overhead valves announced August 1924^[1] supplemented then replaced the Rover 8 air-cooled twin and the new vehicle was named 9/20^[3] The new engine with its clutch and gearbox are mounted as a unit to the mainframe at four points.^[1] z

Advertised by Rover as "The Nippy Nine" with emphasis on its water coolant circulated by pump, pressure lubricated engine, 3-speed gearbox and silent worm (rear) axle. "Super" models were supplied with rod-operated four-wheel brakes. Steering was by rack and pinion, worm and segment in the more expensive cars. At first the open 4-seater cars had just one door beside the front passenger's seat.^[1]

• Standard open 2-seater, open 4-seater tourer
• De Luxe open 2-seater, open 4-seater tourer, fixed head coupé
• Super open 2-seater, 4-seater, fixed head coupé and 4-door 4-seater Weymann saloon
• Sports 4-seater^[4]

The wheelbase was 104 inches and track 48 inches. The 4-seater sports had a 99-inch wheelbase.^[5]

The test car was the sports model with aluminium pistons, double valve springs, higher gear ratios and a lighter body. The car was considered to run pleasantly and do around 60 mph in top gear. When supplied for export the radiator is given a fan. There were complaints about accessibility for servicing and minor repairs. The engine was thought to be unusually smooth for a two-bearing product even at high speed. The steering wheel shook on rough roads otherwise controls were smooth and even. A final comment was "at the price one cannot fairly grumble at three speeds".^[6]