George Russell says Williams could suffer from inconsistent performances this season due to the FW43B's high sensitivity to the wind.
Williams was the only team to allocate a full day of running to its reserve driver, Roy Nissany, in Bahrain which meant that Nicholas Latifi and Russell only spent one day at the wheel of the team's 2021 car.
But strong reliability - a rarity for Williams in past pre-season tests - allowed the team to accumulate a healthy amount of mileage and data, while Russell concluded the weekend an excellent sixth in the pecking order with 158 laps under his belt.
From the knowledge gained by Williams in Bahrain, Russell highlighted his car's extreme sensitivity to windy conditions which he believes could lead to a "yo-yo" season for the Grove-based outfit.
"This test has been a very productive one for the team, we’ve done an incredible amount of laps, no issues reliability wise," Russell commented.
"We knew ahead of the season and confirmed in these days that our car was incredibly sensitive to the wind.
"The conditions of these past three days have brought out the worst of the car – which has been positive in ways to analyse.
"But equally I think you’ll see our performance as a bit of a yo-yo this season and unfortunately quite often in the hands of the wind."
Russell explained that the FW43B's peaky characteristics were expected and were the result of a deliberate choice to add more downforce to the car's design, with the hope that such an approach will pay good dividends this season at a handful of venues.
"We’ve opted to go down a bit of a route to give more downforce, but at the expense of being a bit more sensitive," Russell said.
"That was our decision. Ultimately, we recognised that if we were consistently at a set pace as we probably were last year, we consistently won’t be scoring points.
"You’ve only got to be quick at two races for example and you will potentially finish eighth or ninth in the championship.
"Haas scored three points, Alfa scored eight, we want to try and be as quick as possible when the stars almost align.
"It is uncommon to have three days [of testing] as we’ve just seen with the wind strength so it’s not as though it’s something crazy, every team is experiencing it.
"But it is a small decision we made as ultimately we believe it will produce better results at some races."
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