Mercedes motorsport boss Toto Wolff insists his squad are keeping their feet on the ground and are "never confident" despite their excellent pre-season form.
Although Merc topped the timesheets on only two of the 12 testing days, the statistics were pretty damning for the rest of the pack as Nico Rosberg set the fastest overall time with Lewis Hamilton second quickest.
They also completed the most laps, the drivers used only one engine each during testing and didn't use the super soft Pirellis at all.
With the 2015 season less than a fortnight away, their rivals have admitted that they have quite a big gap ahead of the first race in Australia on 15 March.
Wolff, though, is not getting carried away.
"Never confident," he told F1i.com. "It’s a bit of a boring answer but we’re carefully optimistic that the programme we wanted to do, we did. Lots of mileage, we learned lots of things – not always positive – and it was a great job until now.
"We just need to get our heads down now in the next ten days and analyse properly what needs to be analysed so that we can make the car even better."