The team ran a comprehensive suite of aero checks during this morning's running - aimed at providing data and information for the 2015 car. In the afternoon, the engineers switched their focus to refining balance and set-up for the weekend.

The car responded well on the Prime tyre, particularly during the morning session, but faded somewhat when running the Option in FP2.

Both Jenson and Kevin took part in the FIA's 'virtual Safety Car' running - measuring their pace against a laptime delta - at the end of each session. The test proved useful, highlighting some shortcomings while underlining the benefits of the proposed new system.

Jenson Button: "Our car sometimes struggles in windy conditions, as do I: it's a lot more difficult to be precise when you're driving in the wind. It's in slower corners that we're most affected - such as the start of sector three. And it was certainly very windy today - especially this afternoon.

"The issues with our pace on the Option tyre can be solved. For some drivers, the softer tyre immediately suits their car's balance; for others, it doesn't. It didn't suit ours this afternoon - but we can work around that. We'll get it working tomorrow.

"There were positives and negatives to today's virtual Safety Car test. I like the idea, but you spend a lot of time looking down at your steering wheel in order to ensure you're correctly driving to the delta. If you drop below it when the restart happens, you get a 10-second penalt. In that respect, it's very tricky. With my grid penalty for the gearbox change, it's going to be a difficult weekend. This isn't an easy place at which to overtake, but we'll do our best."

Kevin Magnussen: "This is my first visit to the Circuit of the Americas, and it's a good track. It has a unique first turn, and the high-speed corners in the first sector are especially interesting. I think overtaking should be possible around here, so I hope I can have an enjoyable race.

"Today's running showed that we seem to be stronger on the Prime tyre than we do on the Option. We looked competitive on the Prime this morning, but e need to see if we can find some better pace on the Option. We'll work on that overnight. The virtual Safety Car test worked as it should - it seems like a good idea."

Eric Boullier, Racing Director: "Today was a very busy day. We spent the morning undertaking a comprehensive aero study that will inform the work we do for 2015. It was a productive session, but meant there was a necessary knock-on to our afternoon running, when we have to incorporate much of our usual FP1 learning into the 90-minute FP2 session.

"Perhaps as a result, we looked somewhat less competitive on the Option tyre than we did on the Prime, on which we completed all our morning running. Using the Option, we struggled to find the same sort of laptime improvement as our rivals.

"Nevertheless, we feel we have a good baseline from which to develop for the rest of the weekend, and we'll be working to recover some of that lost pace on the Option ahead of qualifying tomorrow."

Check out our Friday gallery, here.