The car was registered in Chelmsford, according to car registration sites
The grey Hyundai i40, registration plate EX66 RWO, mounted the pavement and slammed into the black railings outside Westminster Palace on Wednesday afternoon.
The vehicle was registered to Chelmsford in September 2016, but according to BBC's Newsnight, the car was rented in Birmingham.
Five people, including the attacker, have died and 40 others were injured in the deadly attack which happened shortly after 2.30pm.
The car ploughed through a crowd of people on Westminster Bridge before driving towards Parliament.
London Terror Attack: LIVE PICTURES Wed, March 22, 2017
Two dead, 12 injured as knifeman mows into crowd in Westminster
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Conservative MP Tobias Ellwood (centre) helps emergency services attend to a police officer outside the Palace of Westminster, London
The car was registered in Chelmsford
Among those killed in the terror incident includes 48-year-old police office Keith Palmer, who was stabbed by the assailant.
A vast swath the crime scene remains cordoned off by police who continue to scour the area for evidence.
Police sniffer dogs arrived at the scene following the deadly attack, while a large police presence still remains in place.
Metropolitan police have increased their presence around the capital in response to the incident.
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Britain’s terror alert threat has not been raised, as the level still remains at severe.
Parliament is expected to convene tomorrow as usual, although parts of the crime scene will remain closed as investigations continue.
President Donald Trump has been in contact with Theresa May regarding the attack.
The area around Westminster remains cordoned off
White House press secretary Sean Spicer condemned the attack and sent his condolences to those affected by the attack.
Express.co.uk has contact Essex police regarding the licence plate.