Ian Chesterton's Volkswagen

By November 1963, Ian Chesterton owned a car. (TV: "An Unearthly Child", PROSE: Doctor Who in an Exciting Adventure with the Daleks, etc.) It was either a Wolseley 4/50, (TV: An Unearthly Child) or a Volkswagen. (PROSE: The Edge of Destruction)

Due to their curiosity about Susan Foreman's incredible knowledge of history and science, and her unique gaps in knowledge regarding present-day culture, such as forgetting that the United Kingdom had yet to adopt a decimal currency, along with her home address being recorded as "76 Totter's Lane", a junkyard, Ian Chesterton and Barbara Wright decided to drive to the address and wait for either Susan or her grandfather to arrive. (TV: "An Unearthly Child")

Alternate timelines
The same course of events naturally took place (COMIC: Prologue: The First Doctor) in an alternate timeline created when an exiled Rassilon allied with the Cyberiad to conquer all of history, (COMIC: Supremacy of the Cybermen) which resulted in the Cybermen capturing the First Doctor before (COMIC: Prologue: The First Doctor) what would be Ian and Barbara's first trip in the TARDIS. (TV: "An Unearthly Child", etc.) This timeline was ultimately aborted. (COMIC: Supremacy of the Cybermen)

Information from non-valid sources
According to one account, Ian's car was an Austin 16. (HOMEVID: "The Pilot Episode")