Car

Cars or automobiles were a common means of transport for humans on Earth in the 20th and 21st centuries. By 2009, there were eight hundred million cars.

20th century
In London, 1924, while on their way to the British Empire Exhibition, the Doctor explained to  Rose that black was the old silver for that time. (PROSE:  The Clockwise Man)

In 1926, Agatha Christie's car was left abandoned by a lake on the night her memory lapsed in the struggle against the Vespiform. (TV: The Unicorn and the Wasp)

In 1951, Eddie and Barbara Smith died in a car crash. (TV: The Temptation of Sarah Jane Smith)

During his exile on Earth, the Third Doctor drove a yellow roadster called "Bessie" (TV: Doctor Who and the Silurians). The Brigadier procured Bessie to persuade the Doctor to work with UNIT after the Doctor had expressed fondness for a similar vehicle he had "borrowed" shortly after arriving on Earth. (TV: Spearhead from Space) A time eddy snatched the Third Doctor, along with Bessie, out of 20th century Earth into the Death Zone on Gallifrey. (TV: The Five Doctors) Bessie remained (in UNIT's care) on Earth when the Doctor regained his time travel knowledge. It was used by his fourth, seventh and eighth incarnations on subsequent visits to Earth. (TV: Robot, Battlefield, PROSE: The Dying Days)

Brigadier Lethbridge-Stewart was occasionally seen to travel in a chauffeur-driven Ford Zodiac staff car. (TV: Spearhead from Space to TV: The Dæmons (intermittently)) He drove the car himself on one occasion, when he used it as a getaway vehicle to escape from the Space Centre following its takeover by General Carrington. (TV: The Ambassadors of Death) His own personal cars were a blue Austin Maxi (TV: Terror of the Autons), and an unidentified white convertible (TV: The Green Death)

While still affiliated with UNIT "post-exile", the Third Doctor also briefly used a different car with a "space-age" look and hovering/flying capabilities. (TV: Invasion of the Dinosaurs, Planet of the Spiders)

Sarah Jane Smith drove many small cars over time, while a companion of the Doctor (TV: Robot, School Reunion) and afterwards. (KAC: A Girl's Best Friend, TV: Invasion of the Bane)

In 1987, Peter Tyler was killed in a hit-and-run incident. Rose Tyler saved his life, causing a massive paradox that made Reapers appear. The car that had killed him disappeared and reappeared across the same stretch of road. To heal the rip in time, Pete was killed when he ran in front of the looping car, killing himself and returning the timeline to normal. (TV: Father's Day)

21st century
During his eighth incarnation, the Doctor used a Volkswagen Beetle that he could drive into his TARDIS. He garaged it in its own alcove. The Doctor traded it for information from the Faction Paradox concerning Samantha Jones whilst in San Francisco in 2002. (PROSE: Vampire Science, Unnatural History)

Mickey Smith used a car to break into Deffry Vale High School by driving straight through the building's glass doors. (TV: School Reunion)

John Ellis used a car to commit suicide by carbon monoxide poisoning. (TV: Out of Time)

Donna Noble had a pivotal moment while driving her car, where turning left brought about her first meeting with the Tenth Doctor. When elements of the Trickster's Brigade caused her to instead turn right, an alternate world was created in which she never met the Doctor, causing his death and dramatic changes to the history of Earth. She travelled in time to correct the error, once again turning left and restoring events to their original course. (TV: Turn Left)

Brian Hopley, Maggie Hopley's husband, died in a car crash. (TV: A Day in the Death)

Luke Rattigan created ATMOS, a device which stopped cars from producing CO2. In actuality, ATMOS would release a gas that would suffocate humans, but allow Sontaran clones to thrive on Earth. ATMOS was also used to control cars and drown those that opposed Rattigan. The Tenth Doctor narrowly escaped from one of these attempts on his life. (TV: The Sontaran Stratagem/The Poison Sky)

When the population of Earth was warp shunted away by the Automatons, the planet's cars were left in place, rather than being allowed to crash. (TV: The Empty Planet)

In 2011, Jack Harkness, Gwen Cooper, Esther Drummond and Rex Matheson, who would eventually form a revived Torchwood team, escaped the CIA in Esther's Mini Cooper. (TV: Rendition) Gwen was later forced to kidnap Jack by car, to take him to Olivia Colasanto's people. (TV: Immortal Sins)

In 2011, the Eleventh Doctor drove a '59 Edsel wagon whilst in Utah. (TV: The Impossible Astronaut) Amy Pond and Rory Williams later wrote a message in a field using their Mini to attract the Eleventh Doctor's attention. (TV: Let's Kill Hitler)

Far future
In the far future, cars such as the New Earth Car could hover. (TV: New Earth) During the time that New New York was under quarantine, the survivors trapped below lived for many years travelling in such cars. (TV:Gridlock)

On Xirrinda, human tourists used auto-piloted cars. Gellen Jenkins used one to escape from the Rain of Terror. (PROSE:  Rain of Terror)

Donna's World
In an alternate timeline caused by the Time Beetle, the poverty of Great Britain following the destruction of London by the starship Titanic meant that the country had far fewer ATMOS installed cars. (TV: Turn Left)

River Song's World
In the alternate timeline created by River Song's refusal to kill the Eleventh Doctor, some cars were transported by large balloons. London had a large number of these cars. (TV: The Wedding of River Song)