SEPANG, Malaysia -- Valtteri Bottas suspects new aerodynamic parts may have been the cause of Mercedes' struggles during Friday practice in Malaysia.
On a track that was expected to suit Mercedes, Bottas and teammate Lewis Hamilton finished 1.4s off Sebastian Vettel's benchmark time in the second practice session. A new aero package -- featuring tweaks to the dive planes on the W08's nose and changes to the bodywork ahead of the sidepods -- was introduced for this round and Bottas believes it may have resulted in a backwards step.
"We did try some new aero parts today, so one answer may be that one of those parts didn't work as expected," he said. "I suppose the new parts are quite a big step, but it didn't quite seem to happen. The team is reviewing everything and we need to make sure we have the right parts for tomorrow."
Bottas explained that the car appeared to lack overall grip, which in turn overheated the tyres when it slid between corners. Once the tyres overheat they fail to offer maximum grip, creating more sliding and a downward spiral in performance.
"The guys are still looking at everything. Normally this track was supposed to be quite good for us, but we were definitively not quick enough. It was not like the car was terrible to drive, the balance felt good, but we were missing grip.
"Normally on Friday you can never be too happy but today we were not far off in terms of balance [between front and rear]. The bigger problem, what we need to find out, is why we're missing grip. We really need to find more grip, somewhere, somehow.
"We were sliding quite a lot, especially in the high-speed corners, and it was the same case in the wet, so we need to find out why. In this kind of track you put so much energy through the tyres that if you slide you overheat the tyres and then it's tricky."