Williams are playing catch-up with their Formula One rivals before the season has even started.
Team bosses told reporters this week that they expected to be adrift of rivals Renault and McLaren, who have looked quick in testing, when the season starts on March 6.
Patrick Head, co-owner of the team and now director of engineering, added that Australian driver Mark Webber had made no secret of his frustration.
"He is clearly disappointed with the performance of the car," said Head. "He realises that the basic car is potentially good but that aerodynamically it is in need of some more downforce.
"He's obviously disappointed by that and knocked back a bit," added the Briton. "I've had a few telephone calls from him and he's not disguising his disappointment.
"But for me to say to him 'Oh don't worry Mark it'll be alright on the day' is not my style.
"I've told him exactly what we're doing but I'm not going to predict that by Malaysia we'll be front row or whatever because I think it'll take a little bit longer than that."