Construction is body-on-frame, which permitted special bodied versions, though the overwhelming majority were built with the standard Pressed Steel Company manufactured steel body shell. A light-weight aluminum alloy was used for doors, bonnet/hood and boot/trunk lid. The chassis is a simple steel box section, welded together and very rigid. The car is 5.38 m (212 in) long, 1.90 m (75 in) wide, and weighs 1.95 tonnes. The engine is a 155 hp / 4000 rpm 4.9 L (300 cu in) six-cylinder unit with inlet over exhaust valves: twin SU carburettors were added in September 1957. The standard transmission was a four-speed automatic, the General Motors designed Hydramatic transmission. The turning circle was 41 feet 8 inches (12.70 m).
Brakes are hydraulic and assisted by the Rolls-Royce mechanical servo with 11 in (279 mm) drums and suspension was independent coils at the front and semi-elliptic springs at the rear. Twin brake master cylinders were incorporated from April 1956.
Power steering and air conditioning became available as options in 1956.
A long-wheelbase version lengthened by 4 in (102 mm) was also made available in September 1957, outwardly very similar to the existing car but offering improved leg space for rear-seat passengers.