Mercedes, Red Bull and Williams show off new cars as testing starts

And Williams and Red Bull also showed off their new cars.

The Mercedes F1 W06 Hybrid had already completed a shakedown run, albeit one halted by a blizzard, at Silverstone on Friday, after which Mercedes released initial pictures of the car.

Both 2014 title-winner Lewis Hamilton and Nico Rosberg tried the car during the Silverstone run, with Rosberg set to carry out the first full test at Jerez on Sunday before handing over to his team-mate for Monday.

[FULL STORY: Mercedes launches as testing begins]

[QUOTES: Nico Rosberg promises 'maximum attack' in 2015]

Red Bull's 2015 Formula 1 car also emerged for the first time, in a camouflage livery, as Jerez testing began on Sunday morning.

The four-time champion team chose not to carry out any form of official launch or car unveiling for the Renault-powered RB11, instead heading straight out of the garage in the surprise colour scheme without ceremony.

Daniel Ricciardo is behind the wheel for the first day of running at Jerez. Toro Rosso graduate Daniil Kvyat replaces Ferari-bound Sebastian Vettel as his team-mate for 2015.

[FULL STORY: Red Bull breaks cover in camouflage]

The Williams Formula 1 team also officially unveiled its 2015 FW37 at Jerez ahead of the first day of pre-season testing.

The British outfit had previously only shown computer renderings of its new car, which were revealed by F1 Racing magazine.

Williams enjoyed a resurgence in 2014 as it became a regular podium finisher on its way to finishing third in the constructors' championship, and team boss Frank Williams said the aim is to continue that upward trajectory this year.

[FULL STORY: New Williams makes first appearance]

Eight of the nine 2015 teams are expected to take to the track for the opening test at Jerez. Force India has already announced that it will not run until the second test at Barcelona later this month.

Mercedes and Toro Rosso are the only teams that have so far shown off their new machines in public, while Ferrari, Williams, Lotus, McLaren and Sauber have released images.

Mercedes - Nico Rosberg

Red Bull - Daniel Ricciardo

Williams - Valtteri Bottas

Ferrari - Sebastian Vettel

McLaren - Fernando Alonso

Toro Rosso - Carlos Sainz Jr

Lotus - Pastor Maldonado

Sauber - Marcus Ericsson