5 Things We Learned from Day 4 of the 2nd 2016 Formula 1 Pre-Season Test

Formula One pre-season testing concluded on Friday, with Ferrari's Sebastian Vettel once again putting in the fastest time. We won't see the cars on the track again until March 18, for Friday practice at the Australian Grand Prix.

After eight days of testing at the Circuit de Catalunya in Barcelona, the teams will be feverishly analysing their data and producing updates to their cars ahead of the first race in Melbourne.

Meanwhile, everyone else will be searching for clues in what we saw and heard from the tests.

The final day of 2016 pre-season testing provided plenty to talk about over the short break until the teams arrive in Australia, from qualifying changes to protective halos to the shrinking gap from Mercedes to Ferrari.

Read on to see what we learned from Friday's running in Spain.

Mercedes Are Not, in Fact, Bulletproof

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Lewis Hamilton on the final day of testing.

Through the first seven days of pre-season testing, the reliability of the Mercedes W07 and its PU106C Hybrid power unit was one of the top storylines. On Friday, though, the final day of testing before the season-opening grand prix in Australia, Lewis Hamilton finally pushed the Merc to the breaking point.

With a strange bang, per the Autosport live blog, Hamilton's Mercedes stopped on the pit straight near the end of the morning session. The team's Twitter account later confirmed a problem with the transmission.

The Silver Arrows had the most impressive reliability record in 2015, suffering just three "did not finish" results between Hamilton and Nico Rosberg, and they racked up 5,396 kilometres in testing this year, but Friday's failure reminds us that even the best of the best aren't perfect.

"I'm glad I broke it!" Hamilton said, per Sky Sports' James Galloway. "It's better to break it now than in Melbourne. I pushed the car here and there, but Australia is when I will really get to open it up."

Over the last two seasons, Mercedes have been so far ahead of the competition that they enjoyed a significant margin of error. If Ferrari (and others) really are closing the gap, though, that margin could quickly disappear, making reliability all the more important.

The On-Again, Off-Again Saga of the New Qualifying Format Is On...Again

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A new qualifying system will be in place for this year's Australian Grand Prix.

First, the Strategy Group and the F1 Commission approved a new qualifying format for 2016. Then F1 CEO Bernie Ecclestone told the Independent (h/t ESPN F1) the software to implement it wouldn't be ready until the fifth race of the season, in Spain.

On Friday, the FIA's World Motor Sport Council approved the new format, per the official F1 website, effective from the Australian Grand Prix, the first race of the new season.

Under the new format, drivers will have time for a couple of laps at the start of the first qualifying session before live eliminations start. At that point, the slowest driver will be eliminated at 90-second intervals, with seven dropping off by the end of Q1 and a further seven by the end of Q2, leaving eight drivers fighting for the pole in Q3.

With the way this has played out so far, would anyone be surprised if there is a software screw-up in Melbourne, leading to yet another public relations black eye for the sport? Let's hope it doesn't happen, but those running the show have not exactly inspired a ton of confidence lately.

Vettel summed up the views of the drivers, telling the BBC's Andrew Benson: "I'm personally not a fan of the new qualifying, and I think speaking on behalf of all the drivers, no driver is. We don't get what's wrong with the old qualifying and why they had to change it."

A 2nd Driver Tested the New Cockpit Halo and Didn't Hate It

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The protective halo installed on Kimi Raikkonen's Ferrari.

Yes, the protective cockpit halo that Ferrari tested this week is ugly. And yes, a lot of drivers have spoken out against it, with Hamilton even saying that he will not use it if it isn't mandatory, per ESPN F1's Nate Saunders and Laurence Edmondson.

The two drivers actually used it in testing, though—Ferrari's Kimi Raikkonen on Thursday and Vettel on Friday—haven't had anything really negative to say about the halo...at least in public.

In typically laconic fashion, Raikkonen said his "first impression on the visibility test is positive. The structure does not hamper [visibility]," according to an FIA press release.

On Friday, Vettel was more enthusiastic in his support for the halo, at least from a safety perspective.

He admitted the aesthetics aren't great but confirmed he did not have any visibility problems and told Autosport's Lawrence Barretto: "If it helps increase the safety and helps save lives, there would be at least two drivers who would still be around—Henry Surtees and Justin Wilson—if we had this type of system.

"It can be ugly, but nothing justifies not having these two guys around any more."

There may be a loud chorus opposing the halo, but the negative noise (at least so far) isn't coming from the drivers who have actually tested it.

Mercedes Have Good Reason to Be Wary of Ferrari's Pace

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Ferrari have demonstrated impressive pace throughout testing.

First, here is the obligatory note that testing times mean nothing.

Having said that, Ferrari once again topped the time sheets on Friday, and that is not some out-of-nowhere performance that we wouldn't expect to continue once the season begins. Rather, it is the continuation of a trend that began last year, when Ferrari became the first team to beat Mercedes on merit in the hybrid V6 era. (Red Bull's three wins in 2014 were assisted by various issues for the Mercs.)

Mercedes executive director Toto Wolff sees the narrowing gap, telling the official F1 website: "They are much closer. It is difficult to say how much closer, but the last couple of days indicate that. It seems they have done a good job over the winter, so it could boil down to a tough fight between them and us." 

Last year, Hamilton may have waltzed to a second straight drivers' title, but he and Rosberg were also glancing over their shoulders at the red cars and, specifically, Vettel. In fact, Rosberg was actually looking up at Vettel in the standings before Hamilton clinched the title and backed off, letting Rosberg swoop in to grab three victories to end the year.

It may still be asking too much for Ferrari to beat Mercedes over a full season, but don't be surprised if Vettel wins more than three races and keeps the title fight much closer than it was last year.

"We know it is close, but we are not sure if we are ahead or behind," said Rosberg on the final day of testing, per Sky Sports' William Esler.

McLaren Are Still a Mystery

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Jenson Button on the final day of pre-season testing.

McLaren certainly look in better shape than they did at the end of pre-season testing last year. 

Fernando Alonso's and Jenson Button's lap times were slightly more competitive than at this point last year. More importantly, though, the car and power unit have demonstrated improved reliability.

After three pre-season tests in 2015, McLaren had managed just 380 laps and 1,751 kilometres with their then-new Honda engines. This year, with just two tests, the MP4-31 clocked 710 laps and 3,305 kilometres. That still left them ahead of just Manor and newcomers Haas, but compared to last year, it must be seen as a win.

After the test, per a team press release, Button said:

"

It's great that we've been able to complete a lot of mileage over the two tests, which has been really useful to get feedback on the power unit, the aerodynamics and a bit of the set-up work done as well. It's also allowed us to do a lot more system checks and integration - which gives us a definite advantage in terms of preparation compared to last year.

"

And pacewise, there should be more to come from McLaren. 

"We haven't run the full 2016 specification yet during the tests, so it means we'll go to Australia with more new parts on the car," said racing director Eric Boullier, according to the same press release.

Assuming the new parts have their intended effect, the team could see another bump in performance. But where exactly will McLaren slot in the overall running order?

We know Mercedes and Ferrari are at the front, probably followed by Merc-powered Williams and perhaps Force India. Meanwhile, Manor, Haas and Sauber seem to be bringing up the rear. McLaren will once be closer to the back than the front, but we'll still have to wait a few weeks to find out exactly where they fit in.

According to Sky Sports' Pete Gill, "McLaren have reached the midfield—but, for now, only the midfield."

Unless otherwise noted, all timing and distance statistics are from the official F1 website.

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