So, apparently, the W10 is heavily affected by wind (which makes sense, given the nature of both the front wing design and the amount of aerodynamically-sensitive appendages the car has).
That's what hurt the W10 in qualifying in Japan.
On Friday, Ferrari looked in no shape to threaten the Mercedes. Ok, so the cars were running old Spec One motors in low modes during practice. But that didn’t explain the 1sec deficit to them. In normal – un-windy – conditions, the Mercedes' downforce advantage through the long corners was decisive. But as well as changing to the Spec Three engines for Sunday, Ferrari reduced the rear wing level, bringing a better balance.
Furthermore, the Mercedes – like the Red Bull – has the loaded outboard front wing, with the full depth elements that give greater direct front wing downforce and contribute to its greater overall aero effectiveness, so long as the outwash around the wheels can be adequately controlled. Achieving that control is somewhat marginal – which is the whole reason it took Red Bull half a season to switch on the RB15. It gives greater downforce than the Ferrari-style unloaded outer wing, but it’s much peakier.
The Mercedes aero team has done a fantastic job of ameliorating that trait with the W10, but Suzuka on Sunday showed that all it takes is a gusty, unpredictable wind, and the car loses some of its sure-footedness. It under-performed here just as surely as it did in the last windy qualifying we had – in Bahrain.
Charles Leclerc was somewhat shell-shocked to be two tenths adrift of Vettel, despite feeling he’d left little, if anything, on the table.
Mercedes was slightly slower in every sector, the drivers just not confident in leaning on it as hard as the Ferrari guys. Valtteri Bottas shaded Lewis Hamilton by a hundredth to go third.
They were over half a second clear of the Red Bulls which had the same problem as the Mercedes but more so and still a power shortfall despite the much-heralded new Mobil fuel for the Spec Four Honda engine. They were running significantly less wing than either Ferrari or Mercedes.