Whomobile

The Whomobile was a futuristic-looking vehicle designed by the Doctor, which was similar to a hovercraft and also capable of flight.

The Doctor first used the vehicle to search for the secret base of Operation Golden Age. (DW: Invasion of the Dinosaurs) It was later used to chase after Lupton when he stole the Doctor's Metebelis Crystal. (DW: Planet of the Spiders)

Behind the scenes
The vehicle, which was also known as Alien, was never given a name on screen. It did not appear at all in the first story's original script or novelisation, both in which the Doctor used a motorbike.

When Jon Pertwee demonstrated the vehicle on an episode of Blue Peter during his tenure, he revealed that the vehicle was road worthy and legal, though he mentioned that the BBC forbids him and any of the crew from removing it from the studios except for outside shoots.