Rubens Barrichello believes only a fundamental improvement from Williams this year will allow it to make any progress in the Constructors' Championship.
The Grove-based outfit has had a disappointing start to the campaign, and is currently ninth in the Constructors' Championship with just four points.
The team ahead of it, Scuderia Toro Rosso, has 17, with Force India another three points clear.
Barrichello believes tinkering with the Williams car will not be enough to lift it into contention to beat its rivals - which is why he is hoping the team can soon find the answer as to why it is struggling.
When asked about the chances of closing the 13-point gap to Toro Rosso, Barrichello said: "If we don't improve what is the fundamental problem - that we keep on testing, experimenting, back to back and things like this, we are going to score points but not in that range - unless we go to the Adelaide type of race where there is a big bang, 15 cars go off and then you finish on the podium.
"The car has its problems, and if we don't go down under and cure the situation to start growing again, and we keep just changing the top, the top, the top, it is just like masking."
Barrichello has said there is no lack of effort from Williams to bring improvement to the car, but he says he is frustrated that updates are not delivering the steps forward that the team hopes for.
"It is not a lack of effort, as Williams is bringing new things," he said. "They are bringing lots of new things but they are not working. Last year some of them did work and then effectively our year improved so much. Right now it is a bit of a situation where we try new stuff, but we are not feeling that they working."