The BBC spent an astounding 18.2 million pounds in 2008-09 on taxis and hired cars, with the daily expenditure coming to almost 50,000 pounds, a media report said on Sunday.
Much of the cost was incurred taking celebrities to and from news studios and driving presenters home when public transport stopped for the day.
Gerry Morrissey, general secretary of Britain's media union Bectu, said he was stunned with the figures.
"At a time when staff pensions are being cut and salaries have been frozen for two years, this is unacceptable," Morrissey was quoted as saying by the Sunday Express.
"We know that many senior executives use taxis as a matter of course and they are not making programmes or on a deadline. What is their excuse? I really would like to know," he said.
Staff were also angry that thousands of pounds were spent on unofficial business and ferrying senior staff and show business stars around London.
They said executives believe having a taxi on call is their "birthright" and so they make little effort to use public transport.
"There is enormous pressure from the top for journalists and programme-makers to account for every penny spent on cars and taxis but huge amounts are still spent on limos for people who quite frankly act as if they are royalty," a staff member said.
A BBC spokesman said: "Guests form an integral part of any 24-hour news broadcaster's output, and audiences expect to hear from a range of expert voices.
"The BBC is a global media organisation and senior executives need to travel when necessary as part of their roles," he said.