The yellow taxi cab belonged to Frances, who after her death inherited it to her grandaugther Phoebe. It is first seen in "The One With Phoebe's Dad", where Phoebe drives it to upstate New York to see her dad, which in the end she didn't. In "The One With The Bullies", Phoebe hits the dog of Frank Buffay's family with the cab. It's also seen in "The One Without The Ski Trip" when Phoebe and her friends, excluding Ross, drive it up to Rachel's sisters ski house. In "The One With Joey's Big Break", Joey drives the cab to Las Vegas and discovers that Frances' ashes are kept in a box under one of the seats. Phoebe and Joey drive it back in "The One After Vegas", when Joey picks up a hitchhiker. In the final episode, the car is used by Phoebe who drives Ross to the airport with it. Ross also refers to it as "The Death Cab", based on Phoebe's driving skills. We also learned that the passenger's seat doesn't have a seatbelt because "the paramedics had to cut through it".