Former Ferrari driver Felipe Massa, now wearing the iconic Martini stripes of Williams' new title sponsor, set the fastest time during the eight test days in Bahrain.
"Nobody has a bad word to say about Felipe or Williams," former team driver David Coulthard told the Daily Mail.
"It's great for formula one," he said. "Massa is a very popular driver across the world, and Frank Williams has formed a popular team."
The newly F1-retired Mark Webber was lured to Williams in 2005 off the back of its "deep roots", but his two-year tenure was at the start of the slump.
The Australian said he would be delighted if Williams' pre-season form was replicated at the grands prix this year.
"It would be brilliant for them to be reliable and strong," he told the Telegraph.
"It would be good, really good, for Frank and everyone, they've been through a tough time but they are a good team," added Webber.
Some of F1's big hitters, notably Red Bull, are not happy that the regulations have changed so greatly.
Williams, however, is thrilled.
"Regulation changes of this magnitude often disrupt the order and create opportunities for teams to make a leap forward," Sir Frank Williams said on Thursday as the new Martini-livery was unveiled in London, according to La Presse.
But his daughter Claire, the deputy team boss, is not expecting world champions Red Bull to be down for long.
"I would be gobsmacked if Red Bull did not (catch up)," she is quoted by the BBC.
"We go to Australia in a good position but we really have to take advantage of the first few races," Claire Williams added.