Lewis Hamilton finished the Jerez test for Mercedes with over 100 laps and the third fastest time of the eight runners out on track. The team haven't been aiming for top speeds, though, instead focusing on reliability, learning about the car and proving their pace over longer runs. Mercedes managed to complete 516 laps across the four days, which is over 100 more than next in line Sauber.

Although there were a few mechanical niggles to be dealt with, the overall outlook is extremely positive for the Brackley team. Hamilton says: "This is where you prove out the car – looking for as many laps as you can, not searching for fast times. It’s been really positive from that perspective and every day here the car has got better as we learn more about it. I can’t really say much about the performance of the car yet but it doesn’t feel any worse than last year’s, which is a good sign. I’m fit and ready to go – 117 laps today felt fairly easy – so I’m already looking forward to getting back to it in Barcelona."

Naturally, the competition are eyeing the defending champions with a wary eye. Felipe Nasr, recently moved to Sauber from Williams, is sure the team are holding back. "I think maybe the Mercedes cars are hiding a little bit what they can do. I didn't see them running what they could do 100 percent."

Not only did the team manage to complete the most laps but they also did the longest runs on four of the six compounds in use. Nico Rosberg managed a 42 lap stint on the harder tyres on day 1, which was the team's most productive day. For them, it's a fantastic position to be in, a positive start to the pre-season testing and the year to come. For everyone else, it's a slightly foreboding performance, proving just what a challenge lies ahead.