Petrol

Petrol, known as gas or gasoline in the United States, (TV: Dead of Night, The Gathering, Hell Bent) was a fuel used for cars. It could be found at petrol stations.

Lack of petrol could cause a car to stop functioning, as it did with Lady Jennifer Buckingham's ambulance. (TV: The War Games) Having diesel in a petrol engine was equally disastrous; the Tenth Doctor used this as an example to explain how an alternate universe was bad for his TARDIS. (TV: Rise of the Cybermen)

Petrol was highly flammable; it was used by Canton Delaware to burn the Eleventh Doctor's Tesselecta body on a boat on Lake Silencio. (TV: The Impossible Astronaut) Explosions could end in "petrol fires". (TV: The Dæmons)

When the Seventh Doctor was reunited with his old car Bessie, his companion Ace asked if it worked on petrol or steam. (TV: Battlefield) Charles Grover had a generator that made tea in his basement that ran on petrol. (TV: Invasion of the Dinosaurs)

Rose Tyler compared charging a TARDIS using the Cardiff Rift to "filling her up with petrol". (TV: Boom Town)

During Miracle Day, CIA members' "gas allowances" were halved; Rex Matheson was way over the limit. (TV: The Gathering)

Alternate realities
In Donna's World, due to the collapse of the UK's economy after London was destroyed by the crash of the Titanic, Britain didn't have much petrol. Due to this, they weren't as affected by the clone feed emitted by the ATMOS as other countries were. (TV: Turn Left)