Robert Kubica has suggested that Williams has to understand the reasons why the same set-up on both its Formula 1 cars is producing different results.
Williams has struggled for performance in Formula 1 this season with its recalcitrant FW42, but Kubica sustained floor damage early in the Australian Grand Prix weekend that compromised his prospects.
Kubica and George Russell also ran different set-ups in Australia but in Bahrain used the same set-up during practice.
Kubica was encouraged by the lessons Williams was able to learn but also perplexed by the issue that it has uncovered.
"The car characteristic with the same set-up is completely different,” he said.
"I had some doubt after Australia, honestly I thought it [the feeling] was caused by floor damages, [but] the floor is in good state here.
"And still even we are using the same baseline set-up as the other car and we have different characteristics and it’s quite significant, something within the aero which is upsetting a lot the handling of the car and general grip of the car.
"We have to wait and see and try to find the answers.”
He added: "In Australia I was struggling, here I am struggling. We thought maybe we went wrong direction with the set-up in Australia so that’s the reason we started with the same baseline set-up as George.
"We can see there’s completely different aero characteristics within two cars so now we have to understand the reasons.
"It’s definitely not helping, it’s quite big, it’s like driving a completely different car."
Kubica finished the second practice session at the rear of the 20-driver field, a second behind team-mate Russell, who placed 19th.
