|1959 to 1961|
|Assembly||Longbridge, England Sydney, Australia|
|Body and chassis|
|Body style||4-door saloon|
|Related||Wolseley 6/99 Princess 3 Litre Vanden Plas Princess 3-litre|
|Engine||2.9 L C-Series I6|
|Wheelbase||108 in (2,743 mm)|
|Length||188 in (4,775 mm)|
|Width||68 in (1,727 mm)|
|Height||60 in (1,524 mm)|
The A99 Westminster appeared in 1959 with new Pininfarina-designed bodywork. Pininfarina had also re-styled Austin's compact A40 and mid-sized A60 Cambridge ranges the year before.
Under the bonnet was the 2.9 L (2912 cc) C-Series straight-6 engine with twin SU carburettors from the Austin-Healey 3000. This engine produced 103 hp (77 kW) in Westminster tune. A three-speed all-synchromesh manual gearbox with a Borg-Warner overdrive unit was fitted as standard, or a Borg-Warner automatic transmission as an option. Power-assisted Lockheed brakes with 10.75 in (273 mm) discs on the front wheels were also new.
An A99 saloon with automatic transmission was tested by the British magazine The Motor in 1960 and they recorded a top speed of 98.1 mph (157.9 km/h), acceleration from 0–60 mph (97 km/h) in 17.9 seconds and a fuel consumption of 23.0 miles per imperial gallon (12.3 L/100 km; 19.2 mpg-US). The test car cost £1219 including taxes. The manual car cost £1148.
A specially trimmed A99 was sold as the Princess 3-Litre, (note, not an "Austin" Princess – Austin was removed from Princess badging during the time of the previous Princess IV, in August 1957) and later under the Vanden Plas marque as the Vanden Plas Princess. A Wolseley version, the 6/99, was also produced. Production ended in 1961 with the introduction of the larger A110.