Summing up the three days of testing that took place in Bahrain on 12, 13 and 14 March, Mercedes is certainly not one of the teams that, at least in appearance, can be defined as satisfied to the maximum with its car.

The first two days were a rollercoaster for the world title holders; they had a few problems, including gearbox issues, which left little time for the two drivers on the track, and consequently more difficulties in analyzing less data than expected.

Valtteri Bottas managed to set the best time in the afternoon session on Saturday, giving a breath of fresh air to the team, also worried about Lewis Hamilton spin.

"Today the wind I think did a 180 so the track is a lot different today and there are some places you can push where you couldn't push yesterday. And it's very gusty, as I found out into Turn 13," the 7-time world champion said.

Things got worse also because of the strong windstorm that hit the Sakir circuit and made things even more tangled for the Mercedes men.
Valtteri Bottas said that despite the wind he could notice that the rear end of the new W12 was tricky to manage:

“It's a bit more windy conditions than we've had normally at the race,” the Finnish driver said.

“But still, I would say one of the big issues with the car is the rear end. It’s quite snappy and it's quite unforgiving."

“That topped up with the new tyres, that they feel quite sensitive to the sliding, it's not that easy. We are kind of trying to calm the car down a bit and that way trying to get some more pace”.

All the teams had to work hard during the winter break to make up for the lack of downforce caused by the introduction of new rules by the FIA.
Tombazis, who joined FIA in 2018 as head of single-seater technical matters, before the season started stated:

"We will eliminate some slots on the side of the car, on the edge of the floor. The rear brake duct winglets, this cascade that lies at the bottom of the brake ducts, we will make that 40mm narrower"

"And the diffuser fences that currently a few of them, the ones that are further in-board and go down to the reference plane, will be limited to the step plane. They will hence be chopped up by 50mm".

"We think that the sum of these changes is approximately 4-5% of the overall downforce the cars have"

"And we of course have made this diagonal trim on the on the floor edge already from May. The total, I think, we expect maybe about 10% reduction.

"And clearly teams will be gaining approximately 4-5% through their normal development - we don't know the exact effects, but these are estimates".

Mercedes, during the presentation of the new single-seater, did not want to disclose the details of the floor to its competitors because Allison claimed to be a very innovative element of the W12.
It is, in fact, very peculiar because below the lateral flow deviators begins a corrugation of the trailing edge with five arches topped by a very conspicuous vortex conveyor. The solution looks like a shell valve.

“As always we really just focused on getting through the programme and maximising the learning and not really looking at lap times,” Bottas said.

“We have no idea what others are testing, and what's going [on with] fuel loads and engine modes, so it’s hard to read yet. Hopefully, by (the) end of tomorrow we could get a bit of an idea from long runs where we are, but still it's only testing," he concluded.