The FW18 (above), unveiled at Estoril yesterday and driven by Damon Hill and Jacques Villeneuve, is an evolution of the car which was generally acknowledged as the best in Grand Prix racing last season.
Adrian Newey, Williams' chief designer, said: "Given that the 17B was competitive, it was sensible to take the root of that car and develop that, rather than come up with a completely new car."
The car features a high-sided cockpit for improved safety, and among the refinements is a revised hydraulic installation, which Williams hope will eliminate some of the reliability problems they experienced last year.
Villeneuve, the IndyCar champion, was in predictably combative mood at the Portuguese Grand Prix circuit. He said: "We're not out there to help each other and there's no reason to. In anyone's career it is important to win and to beat everyone else.
"Even if you finish second in the championship behind your team-mate, after a few years you are not worth anything. It's sad, but because of the way it is, it's almost more important to beat your own team-mate than anyone else."
Hill, whose early season optimism last year was shredded during the course of the championship, is more circumspect this time. He said: "If I am favourite, I would say it was not by a big margin. I think the championship will be very close this season, with wins more evenly spread through teams and drivers. I know it's a mistake to get your hopes up too high.
"I've prepared myself to deal with all the unforeseen problems that may occur during the season. In many ways, I'm more relaxed as I've gone through the learning experience of a toughly-fought championship."
Photograph: John Marsh/Empics