Williams first to reveal their 2015 Formula 1 car

Williams claimed a first by revealing their 2015 car before any of their Formula 1 rivals had taken the wraps off theirs.

With Force India due to show off their new livery at a presentation in Mexico City later, Williams released images of the Mercedes-powered FW37 through their website and the cover of F1 Racing magazine.

Last year's car lifted Williams out of the doldrums to third in the championship and the 2015 version has been reshaped to meet new nose regulations designed to rid the sport of the previous 'ugly' solutions.

Williams chief technical officer Pat Symonds recognised that had posed a 'slight headache' for the designers, with the Williams featuring a shorter nose.

"The new front bulkhead and nose geometry had much more of an impact than we had initially anticipated and the effect on the aero was profound," he said in a statement.

"The team have worked hard on pulling back the deficit these regulations have made for us."

Williams finished ahead of Ferrari and McLaren last season, the first year of the new V6 turbo hybrid era, and behind only dominant champions Mercedes and Red Bull.

With no major changes to the regulations this year, former champions Williams are hoping to challenge for wins and the title with Brazilian Felipe Massa and Finland's Valtteri Bottas but recognised others could close the gap on them.

"The more rule stability there is, the closer the field gets. I hope as a team we are more capable of maintaining the forward momentum to catch Mercedes, than the teams behind us are of catching us," said Symonds.

"It's not just about stable regulations but also about the team and every individual that works here moving forward and improving."

The team announced on Twitter that the Mercedes V6 turbo power unit installed in the back of the new FW37 was fired up for the first time this week.

The first Formula 1 testing of the 2015 season begins at Jerez, in southern Spain, on 1 February.