Nico Rosberg (GER) Mercedes AMG F1. Formula One World Championship, Rd5, Spanish Grand Prix, Race Day, Barcelona, Spain, Sunday, 13 May 2012© Sutton Images.

Race winner Nico Rosberg (GER) Mercedes AMG F1 celebrates on the podium. Formula One World Championship, Rd3, Chinese Grand Prix, Shanghai, China, Sunday, 15 April 2012

Nico Rosberg (GER) Mercedes AMG F1 W03 makes a pit stop. Formula One World Championship, Rd3, Chinese Grand Prix, Shanghai, China, Sunday, 15 April 2012

Race winner Nico Rosberg (GER) Mercedes AMG F1 W03 celebrates on the podium. Formula One World Championship, Rd3, Chinese Grand Prix, Shanghai, China, Sunday, 15 April 2012

Race winner Nico Rosberg (GER) Mercedes AMG F1 W03 takes the chequered flag at the end of the race. Formula One World Championship, Rd3, Chinese Grand Prix, Shanghai, China, Sunday, 15 April 2012

Nico Rosberg (GER) Mercedes AMG F1 W06 and Sebastian Vettel (GER) Ferrari SF15-T battle at Formula One World Championship, Rd4, Bahrain Grand Prix Race, Bahrain International Circuit, Sakhir, Bahrain, Sunday 19 April 2015. © Sutton Motorsport Images

Nico Rosberg (GER) Mercedes AMG F1 W05. Formula One World Championship, Rd15, Japanese Grand Prix, Race, Suzuka, Japan, Sunday, 5 October 2014

Podium (L to R): Second placed Lewis Hamilton (GBR) Mercedes AMG F1, Diego Ioverno (ITA) Ferrari Operations Director, race winner Sebastian Vettel (GER) Ferrari and Nico Rosberg (GER) Mercedes AMG F1 celebrate on the podium at Formula One World Championship, Rd2, Malaysian Grand Prix, Race, Sepang, Malaysia, Sunday 29 March 2015. © Sutton Motorsport Images

Race winner and new World Champion Lewis Hamilton (GBR) Mercedes AMG F1 celebrates on the podium at Formula One World Championship, Rd16, United States Grand Prix, Race, Austin, Texas, USA, Sunday 25 October 2015. © Sutton Motorsport Images

Nico Rosberg (GER) Mercedes AMG F1 W05 leads Lewis Hamilton (GBR) Mercedes AMG F1 W05. Formula One World Championship, Rd15, Japanese Grand Prix, Race, Suzuka, Japan, Sunday, 5 October 2014

Lewis Hamilton (GBR) Mercedes AMG F1 W05 and Nico Rosberg (GER) Mercedes AMG F1 W05 locks up at the start of the race. Formula One World Championship, Rd16, Russian Grand Prix, Race, Sochi Autodrom, Sochi, Krasnodar Krai, Russia, Sunday, 12 October 2014

Podium and results: 1st Lewis Hamilton (GBR) Mercedes AMG F1, centre. 2nd Nico Rosberg (GER) Mercedes AMG F1, left. 3rd Sebastian Vettel (GER) Red Bull Racing, right. Formula One World Championship, Rd15, Japanese Grand Prix, Race, Suzuka, Japan, Sunday, 5 October 2014

Nico Rosberg (GER) Mercedes AMG F1 W05 goes straight on at the first chicane and Lewis Hamilton (GBR) Mercedes AMG F1 W05 takes the lead. Formula One World Championship, Rd13, Italian Grand Prix, Monza, Italy, Race Day, Sunday, 7 September 2014

(L to R): Toto Wolff (AUT) Mercedes AMG F1, Lewis Hamilton (GBR) Mercedes AMG F1, Nico Rosberg (GER) Mercedes AMG F1 and Ross Brawn (GBR) Mercedes AMG F1 Team Principal with the new Mercedes AMG F1 W04. Mercedes AMG F1 W04 Launch, Jerez, Spain, Monday, 4 February 2013