|© AP Photo/Hasan Jamali
Nico Rosberg was the quickest driver and even completed the most mileage on the first of the scheduled two days of the in-season test in Bahrain on Tuesday.
Mercedes' programmes involved running through a sweep of set-up evaluations, with the German clocking a time of 1 minute 35.697 seconds around the Bahrain International Circuit, three-tenths quicker than the Force India of Nico Hulkenberg.
"We've had a good few weeks on track but you are never at the maximum level of performance," Rosberg said. "There is always more to be found and we are constantly pushing to improve the car and also ourselves as drivers."
Fernando Alonso was third in his Ferrari, nearly a second off the pace, ahead of the McLaren of Kevin Magnussen, who was the only other driver to manage more than 100 laps. Williams' Valtteri Bottas was fifth ahead of the Marussia of Max Chilton.
Red Bull was delayed early in the day but eventually got on track and concentrated on long runs and set ups with Daniel Ricciardo.
"We're still a little behind but we're chipping away and I'm sure over the course of this test and in China we'll get a little bit closer," reckoned the Australian.
Sauber fielded Russian teenager Sergey Sirotkin, completing more than 300 kilometres, which is a requirement to receive the super licence.
"In the afternoon we had some difficulties with my shoes. They were too small, so it was pretty painful when I was braking. When we changed the shoes, it was still not the best and difficult to drive," Sirotkin reported about his runs later in the day. "It was not easy."
Robin Frijns’s day was involved with Pirelli, running according to the tyre manufacturer's programme. Caterham, however, ended the day early after a hydraulic system leak with the ninth quickest time on the board.
Pastor Maldonado did the least number of laps as Lotus' troubles with the Renault power unit continued.
Daniel Kvyat was well over four and a half seconds off the pace in last with Toro Rosso focussed on the development of the car in race trim.
"I think this in-season testing is a very useful thing, not just for the teams, but also for guys like me who have to catch up in terms of experience," said the rookie.