Snowflakes are seen on the badge of a Mercedes-Benz car in Warsaw, Poland December 17, 2016. REUTERS/Kacper Pempel

Snowflakes are seen on the grille badge of a Mercedes-Benz car in Warsaw, Poland December 17, 2016. REUTERS/Kacper Pempel

A cable car operator uses a vehicle engine to run the cable car that carries people and supplies to Dhalamlam Mountain in the Jafariya district of the western province of Raymah, Yemen May 20, 2016. REUTERS/Abduljabbar Zeyad SEARCH "MOUNTAINTOP" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

Hubertus Troska, chairman and chief executive officer of Daimler Greater China, is silhouetted against a screen showing a graph of Chinese passenger vehicle market in the past 15 years, as he speaks to reporters at the opening ceremony of the company's Mercedes-Benz research and development (R&D) centre in Beijing November 3, 2014. REUTERS/Kim Kyung-Hoon/File Photo

A forest guard cleans the jeep to be used for safari by Britain's Prince William and his wife Catherine, the Duchess of Cambridge, at Kaziranga National Park in the northeastern state of Assam, India, April 13, 2016. REUTERS/Adnan Abidi

Britain's Prince William and his wife Catherine, the Duchess of Cambridge, sit in a jeep to go on a safari at Kaziranga National Park in the northeastern state of Assam, India, April 13, 2016. REUTERS/Adnan Abidi

Britain's Catherine, Duchess of Cambridge, is seen with her husband Prince William as they sit in a jeep to go on a safari at Kaziranga National Park in the northeastern state of Assam, India, April 13, 2016. REUTERS/Adnan Abidi

Britain's Prince William and his wife Catherine, the Duchess of Cambridge, sit in a jeep to go on a safari at Kaziranga National Park in the northeastern state of Assam, India, April 13, 2016. REUTERS/Adnan Abidi

Britain's Prince William and his wife Catherine, the Duchess of Cambridge, board a jeep to go on a safari at Kaziranga National Park in the northeastern state of Assam, India, April 13, 2016. REUTERS/Adnan Abidi

Britain's Prince William boards a jeep to go on a safari at Kaziranga National Park in the northeastern state of Assam, India, April 13, 2016. REUTERS/Adnan Abidi

Britain's Prince William boards a jeep to go on a Safari at Kaziranga National Park in the northeastern state of Assam, India, April 13, 2016. REUTERS/Adnan Abidi

Britain's Prince William and his wife Catherine, the Duchess of Cambridge, sit in a jeep as they go on a safari at Kaziranga National Park in the northeastern state of Assam, India, April 13, 2016. REUTERS/Adnan Abidi

Britain's Prince William and his wife Catherine, the Duchess of Cambridge, sit in a jeep as they go on a safari at Kaziranga National Park in the northeastern state of Assam, India, April 13, 2016. REUTERS/Adnan Abidi

Britain's Prince William and his wife Catherine, the Duchess of Cambridge, sit in a jeep as they go on a safari at Kaziranga National Park in the northeastern state of Assam, India, April 13, 2016. REUTERS/Adnan Abidi

Britain's Catherine, Duchess of Cambridge,shares a moment with her husband Prince William as they sit in a jeep to go on a safari at Kaziranga National Park in the northeastern state of Assam, India, April 13, 2016. REUTERS/Adnan Abidi

Britain's Prince William and his wife Catherine, the Duchess of Cambridge, sit in a jeep as they go on a safari at Kaziranga National Park in the northeastern state of Assam, India, April 13, 2016. REUTERS/Adnan Abidi

Britain's Prince William and his wife Catherine, the Duchess of Cambridge, sit in a jeep as they go on a safari at Kaziranga National Park in the northeastern state of Assam, India, April 13, 2016. REUTERS/Adnan Abidi

Britain's Prince William and his wife Catherine, the Duchess of Cambridge, sit in a jeep as they go on a safari at Kaziranga National Park in the northeastern state of Assam, India, April 13, 2016. REUTERS/Adnan Abidi

Britain's Prince William and his wife Catherine, the Duchess of Cambridge, sit in a jeep as they prepare to go on a safari at Kaziranga National Park in the northeastern state of Assam, India, April 13, 2016. REUTERS/Adnan Abidi

Britain's Prince William and his wife Catherine, the Duchess of Cambridge, sit in a jeep as they prepare to go on a safari at Kaziranga National Park in the northeastern state of Assam, India, April 13, 2016. REUTERS/Adnan Abidi

A french taxi joins a protest by London cab drivers against Uber in central London, Britain February 10, 2016. REUTERS/Stefan Wermuth

Detail view of the Dodge Challenger Hellcat front lamps while the car is displayed at the North American International Auto Show in Detroit, January 12, 2016. REUTERS/Gary Cameron

A hearse with black flags is pictured outside the St. Michael's Church (Sankt Michaelis) in Hamburg, Germany, November 23, 2015, during the memorial service for the late former West German Chancellor Helmut Schmidt. Schmidt died on November 10, aged 96 and leaders from around Europe praised him as an architect of international cooperation and post-war European integration. REUTERS/Kai Pfaffenbach

Residents go past the building of the Vietnam Asset Management Company in Hanoi, Vietnam October 8, 2015. With a shabby facade, bars on its windows and flanked by a hair salon and a knockoff clothing store, the Vietnam Asset Management Company (VAMC) looks more like a backstreet pawnshop than a much-heralded bad-debt bank. This no-frills office with PVC sofas, chintzy 1980s decor and no elevator houses what's been the central bank's shoestring saviour for wayward banks and risky borrowers who ran up $20 billion in bad debt in 2012 and almost brought a promising economy to its knees. Picture taken October 8, 2015. REUTERS/Kham

A Mercedes-Benz GLA model car kept on display is pictured at a company's event inside a hotel in New Delhi, India, October 14, 2015. REUTERS/Anindito Mukherjee

Newly appointed Managing Director and CEO of Mercedes-Benz India, Roland Folger speaks during a news conference at the launch of company's sport utility vehicle (SUV) GLE model in New Delhi, India, October 14, 2015. REUTERS/Anindito Mukherjee

A Mercedes-Benz CLA 250 Shooting Brake car is pictured at the company booth at the Frankfurt Motor Show (IAA) in Frankfurt, Germany September 19, 2015. REUTERS/Ralph Orlowski

A Mercedes-Benz Concept IAA car is pictured at the company booth at the Frankfurt Motor Show (IAA) in Frankfurt, Germany September 19, 2015. REUTERS/Ralph Orlowski

Various car models of German carmaker Mercedes-Benz are pictured at the company booth at the Frankfurt Motor Show (IAA) in Frankfurt, Germany September 19, 2015. REUTERS/Ralph Orlowski

People visit the booth of German carmaker Mercedes-Benz at the Frankfurt Motor Show (IAA) in Frankfurt, Germany September 19, 2015. REUTERS/Ralph Orlowski

People visit the booth of German carmaker Mercedes-Benz at the Frankfurt Motor Show (IAA) in Frankfurt, Germany September 19, 2015. REUTERS/Ralph Orlowski

Models present creations from Agatha Ruiz de la Prada's Spring/Summer 2016 collection during the Mercedes-Benz Fashion Week in Madrid, Spain, September 18, 2015. REUTERS/Andrea Comas

A model presents a creation from Agatha Ruiz de la Prada's Spring/Summer 2016 collection during the Mercedes-Benz Fashion Week in Madrid, Spain, September 18, 2015. REUTERS/Andrea Comas

Models present creations from Agatha Ruiz de la Prada's Spring/Summer 2016 collection during the Mercedes-Benz Fashion Week in Madrid, Spain, September 18, 2015. REUTERS/Andrea Comas

A model presents a creation from Agatha Ruiz de la Prada's Spring/Summer 2016 collection during the Mercedes-Benz Fashion Week in Madrid, Spain, September 18, 2015. REUTERS/Andrea Comas

Models present creations from Agatha Ruiz de la Prada's Spring/Summer 2016 collection during the Mercedes-Benz Fashion Week in Madrid, Spain, September 18, 2015. REUTERS/Andrea Comas

A model presents a creation from Agatha Ruiz de la Prada's Spring/Summer 2016 collection during the Mercedes-Benz Fashion Week in Madrid, Spain, September 18, 2015. REUTERS/Andrea Comas

A model presents a creation from Agatha Ruiz de la Prada's Spring/Summer 2016 collection during the Mercedes-Benz Fashion Week in Madrid, Spain, September 18, 2015. REUTERS/Andrea Comas

Designer Agatha Ruiz de la Prada (front C) poses in front of her models after presenting her Spring/Summer 2016 collection during the Mercedes-Benz Fashion Week in Madrid, Spain, September 18, 2015. REUTERS/Andrea Comas

A model presents a creation from Ailanto's Spring/Summer 2016 collection during the Mercedes-Benz Fashion Week in Madrid, Spain, September 18, 2015. REUTERS/Andrea Comas

A model presents a creation from Ailanto's Spring/Summer 2016 collection during the Mercedes-Benz Fashion Week in Madrid, Spain, September 18, 2015. REUTERS/Andrea Comas

A model presents a creation from Ailanto's Spring/Summer 2016 collection during the Mercedes-Benz Fashion Week in Madrid, Spain, September 18, 2015. REUTERS/Andrea Comas

Models present creations from Ailanto's Spring/Summer 2016 collection during the Mercedes-Benz Fashion Week in Madrid, Spain, September 18, 2015. REUTERS/Andrea Comas

Models present creations from Ailanto's Spring/Summer 2016 collection during the Mercedes-Benz Fashion Week in Madrid, Spain, September 18, 2015. REUTERS/Andrea Comas

A miniature helmet sits among other helmets belonging to Mercedes Formula One driver Nico Rosberg of Germany in the garage at the pit ahead of the Singapore F1 Grand Prix night race in Singapore September 17, 2015. The Singapore F1 night race begins on Friday. REUTERS/Edgar Su

Helmets for different weather conditions belonging to Mercedes Formula One driver Lewis Hamilton of Britain sit in the garage at the pit ahead of the Singapore F1 Grand Prix night race in Singapore September 17, 2015. The Singapore F1 night race begins on Friday. REUTERS/Edgar Su

Helmets for different weather conditions belonging to Mercedes Formula One driver Lewis Hamilton of Britain sit in the garage at the pit ahead of the Singapore F1 Grand Prix night race in Singapore September 17, 2015. The Singapore F1 night race begins on Friday. REUTERS/Edgar Su

Daimler CEO Dieter Zetsche stands in front of a Mercedes-Benz Concept IAA car during the opening day of the Frankfurt Motor Show (IAA) in Frankfurt, September 17, 2015. REUTERS/Kai Pfaffenbach

German Chancellor Angela Merkel (2L) speaks as she stands with Daimler CEO Dieter Zetsche, President of the German Automotive Industry Association (VDA) Matthias Wissmann and Hesse's state Premier Volker Bouffier (L-R) next to a Mercedes-Benz Concept IAA car during her opening tour of the Frankfurt Motor Show (IAA) in Frankfurt, September 17, 2015. REUTERS/Kai Pfaffenbach

German Chancellor Angela Merkel (2R) stands with Daimler CEO Dieter Zetsche, President of the German Automotive Industry Association (VDA) Matthias Wissmann and Hesse's state Premier Volker Bouffier (L-R) next to a Mercedes-Benz Concept IAA car during her opening tour of the Frankfurt Motor Show (IAA) in Frankfurt, September 17, 2015. REUTERS/Kai Pfaffenbach

German Chancellor Angela Merkel (2R) speaks as she stands with Daimler CEO Dieter Zetsche, President of the German Automotive Industry Association (VDA) Matthias Wissmann and Hesse's state Premier Volker Bouffier (L-R) next to a Mercedes-Benz Concept IAA car during her opening tour of the Frankfurt Motor Show (IAA) in Frankfurt, September 17, 2015. REUTERS/Kai Pfaffenbach

German Chancellor Angela Merkel, President of the German Automotive Industry Association (VDA) Matthias Wissmann (2L) and Hesse's state Premier Volker Bouffier (R, covered) listen to Daimler CEO Dieter Zetsche (L) next to a Mercedes-Benz Concept IAA car during her opening tour of the Frankfurt Motor Show (IAA) in Frankfurt, September 17, 2015. REUTERS/Kai Pfaffenbach

Mercedes Formula One driver Nico Rosberg of Germany attends a meet-the-fans session ahead of the Singapore F1 Grand Prix night race in Singapore September 17, 2015. The Singapore F1 night race begins on Friday. REUTERS/Edgar Su

German Chancellor Angela Merkel listens to Daimler CEO Dieter Zetsche next to a Mercedes-Benz Concept IAA car during her opening tour of the Frankfurt Motor Show (IAA) in Frankfurt, September 17, 2015. REUTERS/Kai Pfaffenbach

Mercedes Formula One driver Nico Rosberg of Germany poses with a Mercedes car during a meet-the-fans session ahead of the Singapore F1 Grand Prix night race in Singapore September 17, 2015. The Singapore F1 night race begins on Friday. REUTERS/Edgar Su

Mercedes Formula One driver Nico Rosberg of Germany poses with a Mercedes car during a meet-the-fans session ahead of the Singapore F1 Grand Prix night race in Singapore September 17, 2015. The Singapore F1 night race begins on Friday. REUTERS/Edgar Su

German Chancellor Angela Merkel and President of the German Automotive Industry Association (VDA) Matthias Wissmann (3R) listen to Daimler CEO Dieter Zetsche next to a Mercedes-Benz Concept IAA car during her opening tour of the Frankfurt Motor Show (IAA) in Frankfurt, September 17, 2015. REUTERS/Kai Pfaffenbach

German Chancellor Angela Merkel listens to Daimler CEO Dieter Zetsche next to a Mercedes-Benz Concept IAA car during her opening tour of the Frankfurt Motor Show (IAA) in Frankfurt, September 17, 2015. REUTERS/Kai Pfaffenbach

The Mercedes-Benz Concept IAA car is presented as German Chancellor Angela Merkel makes an opening tour of the Frankfurt Motor Show (IAA) in Frankfurt, Germany September 17, 2015. REUTERS/Kai Pfaffenbach

A Mercedes is presented at the Mercedes stall before German Chancellor Angela Merkel makes an opening tour of the Frankfurt Motor Show (IAA) in Frankfurt, Germany September 17, 2015. REUTERS/Kai Pfaffenbach