The FW35 will only be driven by race drivers Valtteri Bottas and Pastor Maldonado at the second test, in Barcelona.
Jan.29 (GMM) Susie Wolff will give Williams' 2013 car, the FW35, its track debut next month.
The famous British team has already announced that the Renault-powered single seater will not be at the opening test of the official pre-season at Jerez next week.
Instead, the car will only be driven by race drivers Valtteri Bottas and Pastor Maldonado at the second test, in Barcelona.
But before that, Scottish female driver Wolff, a Williams development driver last year, will be giving the FW35 its actual track debut, at Spain's Idiada facility.
Williams said: "Susie will be the first to get behind the wheel of the FW35 when she drives the car at Idiada next month, and will do the majority of aerodynamic testing this season."
With Susie and her husband now working for rival teams, Toto Wolff this week admitted he has mixed feelings as he starts work as Mercedes' new 30 per cent co-owner and director.
"As a shareholder, you have a commercial obligation as well as a moral one," he told Austrian ORF television this week, referring to Williams.
"There are many people who are dear to my heart, including Frank Williams and his daughter (Claire), and many others," he said.
"You cannot say, one day to the next, 'Now I take off one shirt and put on another. You can't, and I don't want to.
"Now it's a matter of structure, and avoiding conflicts of interest," he said.
Whether or not he eventually sells his Williams shares is unknown.
"That means looking at all options and alternatives, whether Frank Williams buys them back, any of the current investors buys them back or I hold them as long as I think it is acceptable and feasible from a corporate point of view," he told F1 business journalist Christian Sylt, according to the Telegraph.