Even though he completed 90 laps on the final day of testing, Robert Kubica feels the “information was misleading” of the data gained.
Williams had to restrict their testing programme due to lack of replacement components and the wear and tear on the current ones.
The team weren’t able to make an appearance in testing until two and a half days into the first week because of the late arrival of the car.
Kubica said (quoted by Autosport): "We lost another day today.
"Of course we did some laps, but the car's state was far from optimal.
"We had some issues. Unfortunately the car was not representative to what it should be, and this had a big impact on our test, our running programme of today.
"All the information was misleading and in some way also it was difficult to get any information for Australia."
Kubica set his fastest time of testing today, setting a time of 1:18.993, over a second off the pace of Sergio Perez ahead of him.
The Pole said that the lack of spare parts and the delay of the arrival of the car was the reason their Friday wasn’t as successful as it should have been.
"Of course we faced a big delay, and some of today's issues are a consequence of being in a rush," he said.
"If you struggle to have a car for the week before, you struggle to have spare parts.
"And unfortunately today it was required to have bits to replace, and we couldn't replace them.
"In the end we did the maximum from what we have, but this maximum is not enough, because in the end the car was from optimal."