Police are investigating the theft of Princess Beatrice's black BMW, which she reportedly left unlocked with the keys in the ignition while she went into a London shop.
The car was a 17th birthday present to the princess from her father, Prince Andrew, The Sun newspaper reported.
Police have confirmed that detectives are investigating a car theft from a London street. But the force would not say who owned it or confirm reports it had been left unlocked.
Buckingham Palace would not comment.
The 20-year-old Beatrice, elder daughter of Andrew and Sarah Ferguson, is fifth in line to the British throne. She receives round-the-clock protection from a police bodyguard.