Acclimatising to the most sweeping rule changes in the sport's recent history - in particular the new V6 turbocharged engines - largely dictated the tempo in Spain this week.
Red Bull suffered most, clocking up just 21 laps across the week as overheating issues, coupled with wider power unit dramas for Renault, blighted its early preparations.
Mercedes in contrast looked ominously strong as both a constructor and an engine supplier.
Jerez F1 test gallery
While that figure was ultimately the most important barometer for teams given the sheer number of new processes to learn and assimilate, McLaren still had the honour of setting the early season pace courtesy of its new rookie recruit.
Magnussen hit the front on his first official day as a grand prix driver, and with day four affected by poor weather his 1m23.276s was enough to seal top spot by just under half a second.
Felipe Massa was his nearest challenger, as a strong start to life with Williams left him second overall and top in the slippery conditions of the final day.
Hamilton, Jenson Button and Valtteri Bottas emphasised Mercedes' emphatic start by all sealing top-six spots, with Raikkonen (fifth) and Alonso (seventh) the only non-Mercedes-powered drivers in the top 10.
The latter, along with several others, moved on to attempting much longer runs in the final afternoon, only for their stints to be scuppered by a trio of red flags - the latter two for Magnussen, who ended his test in the Turn 10 barriers.
That meant Rosberg was the first and only man to do a full race simulation, putting the seal on the German manufacturer's resounding opening to F1's new era.