Williams set the fastest time as pre-season testing drew to a close in Barcelona on Sunday.
Lewis Hamilton topped the timesheets on his final day of testing ahead of the Formula One season on Saturday.
Nico Rosberg sent out an ominous warning to the rest of Formula One by setting the fastest time in Barcelona.
McLaren's Fernando Alonso has told fans that he is well after crashing heavily in testing last weekend.
Marussia's return to Formula One has been approved by the sport's FIA governing body.
Lewis Hamilton and Jenson Button suffered technical issues on the first day of F1's final pre-season test in Barcelona.
McLaren expect Fernando Alonso to recover from Sunday's crash in time to race in the season-opening Australian GP.
Lotus have signed Spain's Carmen Jorda to the role of development driver for the 2015 season following three years in GP3.
Fernando Alonso has left hospital but will miss this week's final pre-season testing following his crash on Sunday.
Britain's Will Stevens has been named as the renamed Manor team's first driver for 2015.