Is Ferrari really as quick as the Jerez timesheets suggested? And when will Mercedes reveal its hand? Kate Walker asks the crucial questions.
As the Formula One teams gather at Barcelona's Circuit de Catalunya for the second week of 2015 pre-season testing, it is to a barrage of questions that they either cannot – or do not want to – answer.
With preparations for the season now well underway, the goal of the teams is to press ahead with planned development programmes while hoping to be free from gremlins.
Those in need of sponsors will do the occasional glory run, but real hints of true pace will not come till the final week of testing, and more likely during free practice in Albert Park one month from now.
What was remarkable in Jerez was the lack of problems we saw on track.
McLaren may have spent the bulk of the week in the garage, fiddling around with the new Honda power unit, but in terms of on-track stoppages and smoking bits of tightly-package bodywork, there was far less to be seen than is traditional at the first test of the year.
Those teams who were able to avoid reliability troubles at the beginning of the month will be crossing their fingers that Barcelona brings more reliability and endless track time so that development work can begin in earnest.
On the other end of the scale, McLaren - and, to a lesser extent, Red Bull and Lotus - need to get significantly more running under their belt if they are to have a hope of being competitive at the first four races.
Lotus and McLaren are both adjusting to new power units this year, and while the Enstone-based racers were only able to complete 190 laps of the Jerez circuit across three days' running, the E23 Hybrid spent the first day of the test in transit to Spain.
When Lotus's test belatedly began, it was not trouble-free: Pastor Maldonado had an early finish on his first day out with drivetrain issues, and on the second day lost the morning to telemetry troubles, while on the final day Romain Grosjean called it quits in the early afternoon thanks to power unit problems.
Red Bull form a mystery
Red Bull may be working with familiar engine partner Renault, but after a less-than-smooth transition to the new 2014 hybrid power units, the winter saw both parties hard at work, trying to close the gap to Mercedes.
Jerez did not run entirely according to plan – Daniil Kvyat spent a day running without a front wing after damaging the only model early on, while the RB11 suffered a number of battery failures, power unit problems, and issues with internal power unit components both large and small over the four days.
With major modifications hard to bring in during the first four flyaway races, the next eight days of testing at the Circuit de Catalunya will be vital to the teams' attempts to iron out any serious problems before the cars are sent to Australia.
Whatever positive statements make their way into the official press releases, a lack of running here will be a serious hindrance to anyone's planned development programme.
Still no new Force India
Force India has been playing a game of hokey-cokey with testing, doing a will-they won't-they dance with the press over the presence of their 2015 car in Barcelona.
As things currently stand, the team – whose troubles have been well-documented – will be running the VJM07 during the first week of Barcelona testing, with the VJM08 not making its debut till the final four days.
It's risky ground for the Silverstone racers, whose only advantage is the continuity in their relationship with both their driving line-up and engine suppliers Mercedes. There will be little of value for the casual observer to learn from this week's test, but at least we will get a look at Mercedes's reserve driver Pascal Wehrlein for a couple of days in its car.
Is Ferrari's pace real?
Both Ferrari and Sauber impressed on the timesheets in Jerez, but it'd be best to hold tight before betting the house on a constructors' title for Maranello this year.
It certainly looks as though Ferrari has made a much-needed step forward with the power unit over the winter, but it was also clear that none of the Mercedes-powered teams were running with laptimes in mind.
Both Sebastian Vettel and Kimi Raikkonen were reasonably pleased with the SF15-T, with the Finn saying he felt more confident in it than he had the previous model, but what was interesting was the post-session remarks of the Sauber drivers, who were twinned with the Ferrari drivers at the top of the timesheets each day.
Felipe Nasr and Marcus Ericsson were both positive about the C34, but both men also conceded that part of the car's pace could be attributed to a lack of downforce.
Seeing how they perform at the much more representative Barcelona circuit will give a better indication of the Sauber's overall balance, which will in turn help provide a frame of reference for the Ferrari.
Mercedes to seek performance
Having completed a record number of laps on the first day of testing, Mercedes had an ideal start in Jerez. The car did not run perfectly, but problems were by and large quick to resolve and the W06 completed more than five race distances across the four days' running.
With long runs and aero testing already underway at the first test, and signs of their true pace unlikely until the final test, the Silver Arrows will be aiming for another week of solid data-gathering and development work.
Another team whose year got off to a good start in Jerez was Williams, and like engine suppliers Mercedes the Grove racers will be looking to repeat a solid first week that saw the team complete long runs and qualifying simulations while also conducting some much-needed aero development work.
Finally, Toro Rosso – bedding in new drivers as well as a new car – had a solid start to winter testing, with a few minor teething troubles over the course of the first winter test.
Despite the Renault engine issues, its STR10 was second only to Merc's W06 in terms of laps logged at Jerez, and with the reliability boxes ticked in the first week of pre-season tests, the next two weeks at Barcelona will see the Faenza-based team's focus on performance as it continues to develop its rookie drivers.
Barcelona test line-up
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