A new Hawk announced in May 1957 had a completely new body with unitary construction which it would go on to share with the 1958 Humber Super Snipe. The new model was, like its predecessors, a large car. For the first time an estate variant was available from the factory - the Hawk estate had the largest unitary bodyshell of any British-built car up to that point, a status it retained until the Jaguar Mark X was launched in 1961. The 2267 cc engine was carried over, though with modifications to the distributor mounting, and other details; and an automatic transmission, the Borg Warner D.G. model, was now available. The body was styled in Rootes' own studios and featured more glass than previous models, with wrap-around front windscreen, which gave it a considerable resemblance to a base model 4-door sedan. The missing rear quarter-lights were returned in Series IV. The estate version featured a horizontally split tailgate—the lower half opening downwards (to provide an extra length of luggage-platform if necessary) and the upper half upwards. The fuel-filler cap was concealed behind the offside rear reflector.