[6] The chassis was designed by Paddy Lowe, Neil Oatley, Tim Goss, Andrew Bailey and John Iley and was powered by a customer Mercedes-Benz engine.

It was launched on 1 February at the McLaren team base in Woking, Surrey, ahead of the first winter test sessions at Jerez de la Frontera.

[10] Button went on to win the race, with Hamilton finishing third despite team principal Martin Whitmarsh's admission that the team had made a mistake in calculating Button's fuel load, forcing the 2009 World Champion to enter a "severe fuel-saving mode" on the eighth lap of the race.

[13] At the Chinese Grand Prix, the Mercedes cars found pace, allowing Nico Rosberg to take his first pole and win.

Button started fifth and finished second; Hamilton initially qualified second, but a gearbox change set him back to seventh before he fought through to third place.

[15] In the Bahrain Grand Prix, Hamilton finished in eighth and Button retired whilst running in seventh, with the former being compromised by a slow pit stop.

Button continued his dismal form by finishing 16th as he struggled due to tyre problems which resulted in a complete lack of pace in a track which he won last year.

In Valencia, despite Hamilton's send place in qualifying, he was unable to match the pace of Vettel and Alonso in the race and then during his 2nd pit stop, the front jack failed, causing him a delayed pit-stop.

To top off his day, he collided with Pastor Maldonado while battling for third place and hit the wall in the closing stages of the race, ending his chances of a podium finish.

Hamilton could only manage eighth, while Button qualified 18th, but was promoted to 16th due to penalties of Kamui Kobayashi and Vergne from Toro Rosso.

[22] It became clear that the car might need significant updates before the German Grand Prix so as to improve recent poor results and get back to winning ways.

Both drivers were promoted to sixth and seventh respectively due to Mark Webber's gearbox change which resulted in a 5-place grid drop.

[24] During the Hungarian Grand Prix, the efficiency of the upgrades finally showed as the qualifying session was held in dry weather.

Lewis Hamilton recovered after the disappointment in the German Grand Prix, he was dominant in every practice and qualifying, achieving McLaren's 150th pole position.

Button qualified on pole and would dominate the race to take his 14th career victory, his first time at Circuit de Spa-Francorchamps.

The result serves as a small consolation for a mixed season for the team, as they also lost 2nd place to Ferrari in the Constructors' Championship.