Princess Beatrice and Princess Eugenie are carrying out their first joint overseas engagement.
The royal sisters will travel to Germany for a two-day tour promoting the UK as part of the Great Campaign - a global initiative to attract visitors, business and students to the UK.
The Princesses will drive a Mini, emblazoned with the Union flag, the short distance from the Brandenburg Gate in Berlin to the British Embassy.
The event launches the Great Britain Mini tour across Germany, a trip which will showcase the very best of British - from culture and technology to music and innovation.
During the day the royals will travel around Berlin attending a range of events, from a fashion fair to support the British textile industry to meeting the UK team of a German online shop.
Beatrice, 24, said to work for a venture capital firm, and Eugenie, 22, who is completing a series of work placements, will spend Friday in Hanover highlighting the heritage and knowledge elements of the Great Campaign.
The royal sisters will attend the reopening of Herrenhausen palace, meet members of the Lower Saxony and Hanover administrations, and visit other historical sites.
A Buckingham Palace spokeswoman said: "They were asked to do it by Number 10 to support the Great Britain campaign and they were happy to do it.
"It's all about raising awareness of the UK as a great place to visit or do business with."
She added that Beatrice and Eugenie's father, the Duke of York, will pay for their travel expenses from his private funds.