The all-new Mark IV Super Snipe announced mid-October 1952, Earls Court Motor Show time, used a Hawk Mk IV body shell lengthened by 6 in (152 mm) but with a 4138 cc 113 bhp (84 kW) overhead-valve engine also used in a Rootes Group Commer truck. Chassis and suspension components were uprated to take the greater weight and power of the Super Snipe, those parts ceasing to be interchangeable with those of the Hawk. From 1955, overdrive was available as an option, followed in 1956 by an automatic gearbox.
Shortly after the car's announcement Leslie Johnson, Stirling Moss, and two Rootes Group staff, drove a new silver-grey Super Snipe from Oslo to Lisbon, travelling through fifteen European countries in 3 days, 17 hours and 59 minutes. The run demonstrated the car's high-speed reliability in far from ideal conditions.
In 1953 The Motor tested a Mk IV and found the larger engine had increased performance with the top speed now 91 mph (146 km/h) and acceleration from 0-60 mph (97 km/h) in 14.7 seconds. Fuel consumption had increased to 15.5 miles per imperial gallon (18.2 L/100 km; 12.9 mpg‑US). The test car cost slightly more at £1,481, including taxes.