Williams are looking to move on in 2016 after a season of consolidation

Williams are developing a "significantly different" car for the 2016 season as they bid to take the next step in their revival.

The nine-time constructors' champions finished this season in third place for the second successive year, the first time in a decade they have secured back-to-back placings in the top five.

Having slumped to ninth in the standings as recently as 2013, Williams' campaign represented overdue consolidation - although they scored fewer points and podiums than the year before.

And knowing they need to take another big step forward again over this winter if they are to challenge Mercedes and Ferrari, Rob Smedley, the Grove team's head of vehicle performance, hints the team are working on some new design concepts for their FW38 challenger.

"The car that we've got in the wind tunnel for 2016 and our end-of-season 2015 car are significantly different," Smedley said.

"Everything we're seeing at the moment is good. We're hitting targets and we are always looking not just at headline numbers, but other significant areas of aerodynamic development.

"It's a process of getting us back towards the front."

Bottas and Massa claimed two podiums apiece in 2015

Although Williams finished a comfortable 70 points ahead of fourth-placed Red Bull, Smedley concedes their late-season form was "slightly lacklustre" - particularly at the season finale in Abu Dhabi, where they finished eighth and 13th just 12 months after claiming a double podium at the same venue.

However, the Englishman points out that they stopped bringing updates to the FW37 a number of races before the end of the season.

"We stopped development on this car quite a long time ago, having projected forward that we would have a comfortable third position in the championship and second wasn't going to be possible," he said. "So a natural amount of what we're seeing is due to the fact that we just haven't developed the car in such a long time.

"When we are developing the car correlation with the wind tunnel is very good and that transpires into lap time. The end of the season has been slightly lacklustre compared to last year, but last year we developed the car right to the end of the very last moment."

Although back in regular podium contention over the past two seasons - Williams 13 podiums in 2014-15 are one more than they managed in the previous 10 combined - the team are yet to win in F1's current turbo era.

Sky Sports F1's Ted Kravitz and Martin Brundle give their verdict on the teams performances in the paddock for 2015 Sky Sports F1's Ted Kravitz and Martin Brundle give their verdict on the teams performances in the paddock for 2015

Rating all 10 teams' performances in 2015, Sky Sports F1's Martin Brundle said it was important Williams now kicked on.

"In a way I think it's a bit of a disappointing year for Williams," said Brundle, who raced for the team in the 1988 Belgian GP.

"They probably underestimated Ferrari's advance, like so many did, and they need to invest again now.

"They've stabilised the ship, they're back at the front, they keep their nose clean with Mercedes and have got the best power pack, now this winter they've got to move forward."