Mercedes raised the bar again to win 2015 title - Dieter Zetsche

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The chairman of Daimler and overall head of Mercedes Dieter Zetsche says his Formula One team had to up its performance to secure its second constructors' title in as many years this season.

Mercedes wrapped up the title at the Russian Grand Prix after Lewis Hamilton won the race and a post-race penalty for Kimi Raikkonen saw Ferrari fall out of contention.

"What an incredible moment for Mercedes-Benz," Zetsche said. "Congratulations to our team in Brackley and Brixworth who have worked so hard to make this achievement possible, winning a second world championship in a row. After winning in 2014, we raised the bar again to secure this year's title, and we needed to because our rivals gave us plenty of headaches as they stepped up their performance.

"The work by our team is the perfect example of what drives Mercedes-Benz forward: the best technology. The most efficient hybrid petrol engine that our company has ever made, world-beating aerodynamics and intelligent design in every part of the W06 Hybrid racing car.

"Most importantly, though, we must not forget the human factor: we have two exceptional sportsmen at the wheel, Lewis and Nico, and a fantastic team behind the scenes, who have delivered 12 wins in 15 races so far this year. Their work has made every employee of Mercedes-Benz a world champion and we are very proud of them."

Speaking ahead of the race, team boss Toto Wolff said Mercedes' success was thanks to all the members of the team.

"What makes me particularly proud? It is such a big group of individuals working so hard in Brackley, Brixworth and Stuttgart," Wolff said. "And maybe it sounds boring me repeating that, but it is an achievement having built a car and an engine that is very dominant in an era. We have held the team together and we haven't lost many people.

"We have had difficult races like Malaysia this year when suddenly we have a bit of a surprise where we lost the race and then Singapore, but you need to just come out of it with a calm approach and had a good day here today. How the team keeps developing is nice to be a part of and it is a real team effort where everyone works in the team from the engineering side to the comms side to the marketing, it is just a good little group of people sticking together."