While Rosberg had set the early pace, it was left to Mark Webber to lead the pursuit of Button at the head of the times. The Australian concentrated on tyres amongst other basic evaluations, but came through late on to pip Romain Grosjean for second spot.
"It was pretty good,” he claimed, “As Adrian [Newey] said at the launch, there haven't been big changes to the regulations this year and the car is an evolution of the one we finished with last season, so there were no big surprises. I think most of the drivers will sit back tonight and think today's times were pretty competitive.
“It was actually like a Friday practice session in some regards. We started understanding the tyres and there were a lot of positives. There's a bit of housekeeping we have to get on top of but, other than that, it's been encouraging. The car feels similar to last year's, so the main difference is the tyres. With these tyres, you're always on your toes. Generally though, the car feels pretty good, so I'm happy.”
Grosjean, like Rosberg and Paul di Resta before him, also enjoyed time at the top of the charts, but had to settle for third spot as the chequered flag brought the end to a solid day's work for the Lotus team. The Frenchman was the fastest man on track for much of the day, as the team completed 54 laps of systems checks, temperature monitoring, data correlation and early aero evaluation on the E21.
“The feeling is good [and the car] feels very similar to the E20 from behind the wheel, even if it does look different from the outside,” he commented, “Once again, Enstone has produced a car that is quick from the very first lap. We spent a little bit more time than ideal in the garage today, but that's normal in testing. I'm happy we completed 54 laps, and even happier that all of them were quick. We now have a good idea of the new tyres and we'll have some challenges from them - the grip level is there but performance does fall away with graining. That said, Jerez is a very specific track in this regard. The speed came easy today and we didn't respond to the other cars going faster in the afternoon. We should go even better tomorrow.”
di Resta was also encouraged by the initial performance of the new Force India, running in the lead quartet for much of the day.
"It was a positive first day and we managed to cover lots of laps - so that's the most important thing,” the Scot confirmed, “I felt very comfortable all day and we managed to get through the programme as we focused on collecting aero data and understanding how well the car correlates with our simulation tools at the factory.
“We also started trying to learn as much about the tyres as possible so that we can carry that into tomorrow and optimise the set-up. The new compounds are quite different with the new construction and I've already felt a difference with the balance of the car in the low and high speed parts of the lap.”
di Resta ended the day a tenth clear of Toro Rosso's Daniel Ricciardo, who enjoyed a largely trouble-free day at the wheel of the Italian car unveiled on the eve of testing . After the usual installation laps, the team began tackling a programme which centred on checking all systems without looking at performance – although, inevitably, the engineers could not resist looking at the aero numbers for the new car!
“It's good to be back behind the wheel of an F1 car,” Ricciardo commented, “It was a long day to complete 70 laps, however, the main thing is that the car was reliable, which is a positive aspect and we got through our work schedule for the day.