Construction was 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 aluminium-based alloy was used for doors, bonnet/hood and boot/trunk lid.
The chassis was a simple steel box section, welded together and very rigid.
 The car was 5.38 m (212 in) long, 1.90 m (75 in) wide, and massed 1.95 tonnes.
The engine was 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 sourced Hydramatic transmission.
The turning circle was 41 feet 8 inches (12.70 m).

Brakes were 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.

The British Motor magazine tested a standard-wheelbase factory-bodied Series I in 1956 recording a top speed of 102.9 mph (165.6 km/h) and acceleration from 0-60 mph (97 km/h) in 13.5 seconds and a fuel consumption of 14.5 miles per imperial gallon (19.5 L/100 km; 12.1 mpg‑US).
The test car cost £5078 including taxes.
Construction was 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 aluminium-based alloy was used for doors, bonnet/hood and boot/trunk lid. The chassis was a simple steel box section, welded together and very rigid.  The car was 5.38 m (212 in) long, 1.90 m (75 in) wide, and massed 1.95 tonnes. The engine was 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 sourced Hydramatic transmission. The turning circle was 41 feet 8 inches (12.70 m).
Brakes were 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.
The British Motor magazine tested a standard-wheelbase factory-bodied Series I in 1956 recording a top speed of 102.9 mph (165.6 km/h) and acceleration from 0-60 mph (97 km/h) in 13.5 seconds and a fuel consumption of 14.5 miles per imperial gallon (19.5 L/100 km; 12.1 mpg‑US). The test car cost £5078 including taxes.
Rolls-Royce Silver Cloud