The alert did not affect flights, but police warned motorists to stay away to minimise traffic congestion.
Part of the south terminal was evacuated and the A23 road leading to it closed. Trains on tracks close to the cordoned-off area were stopped, including the Gatwick Express from London, Victoria.
Inspector Gavin Whitehouse of Sussex police said that a member of the public had alerted police to the vehicle shortly before 9pm. After investigating, police decide to call in the army's bomb disposal unit. However, police sources said last last night that the unit did not believe the vehicle was a threat.
The airport's north terminal was unaffected throughout, while travellers arriving for flights from the south terminal were led in through an alternative entrance.
The evacuation was the latest in a series of security alerts in and around London airports. In February a man was stopped by customs officers after a hand grenade was allegedly found in his luggage as he arrived at Gatwick.
Hasil Mohammed Rahaham-Alan, a 37-year-old Venezuelan, was charged with possessing an article for the purpose of committing a terrorist act, possessing an explosive substance with intent to endanger life or damage property, and carrying a dangerous article on an aircraft.
At Heathrow airport in February, a specific threat led to a high-profile security operation that included the deployment of light tanks. More than 400 soldiers and about 1,700 extra police officers were drafted in to the airport and other London locations.
It was believed that the threat referred to the possibility that terrorists could attempt to shoot down a civilian airliner with a shoulder-held rocket launcher.
