The team is upbeat about the early performance of the FW35, having shown some promising speed and solid reliability since the car was launched at last week's Barcelona test.
Technical analysis of the Williams FW35
And although mixed weather conditions have made it difficult to judge the relative performance of the teams so far, Williams chief race engineer Xevi Pujolar is happy with how things are looking for the team ahead of the first race.
"The areas where we were weaker last year we improved, now we need to see if we improved enough," he said, when asked by AUTOSPORT for his verdict on where the new car is better over its predecessor.
"For us we are happy with what we have got. You always want to get more, but now it is always a bit difficult - now it is so dominated by the tyres so we need to see.
"Even when you do long runs, it depends on what happens with the graining or how much fuel you put in.
"It could be that you go to Melbourne and you grain the tyres as well, or it could be like we had in Barcelona last week."
Pujolar thinks that the fact Williams was the only team to run its old car at the first test has given it is a better indication of where it stands against the opposition than those who have only run with the new cars.
"Last week we had a good test for us, although it was difficult to know what everyone is doing," he explained.
"The previous week we were in Jerez with last year's car, so we had a reference on the tyres. We know where we were with the tyres, so now you compare tyres.
"We are happy we have done a step forward and did a lot of mileage last week. The car is reliable and now we need to see what everyone has done when we get to Melbourne."
AUTOSPORT special testing coverage:
Gallery Testing blog Technical blog Live commentary
- Sports & Recreation