The Prime Ministerial Car refers to a number of British manufactured vehicles used by the Prime Minister of the United Kingdom. The vehicles currently used are armoured, custom built Jaguar XJ Sentinel supercharged 5.0-litre V8 models. Prime Ministerial and ministerial limousines are operated and administered by the Government Cars Agency, an executive agency of the Department for Transport, and stored and maintained at 10 Downing Street. The cars are driven by specially trained UKSF close protection drivers, and are escorted by unmarked Range Rovers and Protection Command officers.

The current model fleet was first seen in use on 13 May 2010 when newly appointed Prime Minister David Cameron arrived at 10 Downing Street.

More Info: en.wikipedia.org