Hubcap Hovercraft

This is a sci-fi trope in which a wheeled vehicle of some kind is capable of flying or hovering by simply rotating the wheels 90 degrees, usually up and into the vehicle in question. The hubcaps then become thrust-capable engines, catapulting the vehicle upwards.

Comic Books

 * SHIELD hovercars, in many depictions.

Film

 * The DeLorean from Back to The Future. Turns out that by 2015, all cars can undergo a "hover conversion" like this.
 * Mater in UFM: Unidentified Flying Mater.

Literature

 * Although it doesn't use this for flying, Ian Fleming's Chitty Chitty Bang Bang may be the Trope Codifier. To wit: the Pott family is picnicking on a beach, and the tide comes in. Mr. Pott turns a knob, causing Chitty's wheels to turn down and out in this manner. The car glides along the water exactly like a hovercraft.

Videogames

 * S.O.P.H.I.A. the 3rd and all of her variants from the Blaster Master series.
 * Many of the ground-based Transformers from Transformers War for Cybertron.
 * The versatile hoverpod powerup in Vigilante 8 Second Offense that levitates sportscars, motorbikes, R Vs and garbage trucks alike.

Western Animation

 * The short-lived Pole Position cartoon of The Eighties featured a pair of talking hovercars.