McLaren continue to push on with development of the MP4-31 which bore fruit in Barcelona, with Alonso able to make Q3 and Button eventually taking 9th place on race day.
The front wing has been under intense scrutiny since Peter Prodromou arrived from Red Bull. At the Spanish GP the team made another step forward, with what those in the team are describing as the first iteration in a new lineage of designs.
The wing, like many others on the grid, compartmentalises the functions that need to be undertaken hoping to improve not only its performance but other aerodynamic devices downstream. Changes to incorporate a more deliberate tunnel at the outboard section have been made, with an ever increasing tunnel funnelling air around the front tyre to control the wake it sheds . The tunnel is flanked by a continuation of the flap slots all the way until they terminate at the endplate , which help to control how the airflow moves and is released from it. The footplate  now has a more deliverate funnel shaping in order to expand the airflow and assist the other structures around it. The endplate has also been revised , with a window allowing airflow to migrate outboard, also shaping the air as it moves around the front tyre.
The vane that hangs from the main cascade is now joined by another , which will work together to retarget the airflow as it passes over the front face of the tyre.
Lastly, the flaps have also been revised not only in shape but at their tips too . Rather than simply finishing at a point they have now have two separate sections, which will change the rotation of the Y250 vortex shed at the juncture of the neutral section and flapped mainplane below.
Only one of the new specification wing was available in Spain, with Button exclusively using it throughout the weekend, whilst Alonso continued with the previous specification.
The team also revised their front brake duct once more, making somewhat of a sea change and abandoning their open finger style duct they’ve been using for some time (smaller inset). Aside from the external changes the internal brake drum was also revised further, having already been amended in Russia. These changes are focused on the thermal management of the tyres, with heat from the brakes radiating into the wheel rim and then into the the tyre itself.
There were some minimal changes to the rear wing in order to suit the characteristics of the Circuit de Catalunya too. Changing the shape and angle of attack of both the mainplane and upper flap.