F1 in 2018: Five key questions before the final week of winter testing

Will Mercedes and Lewis Hamilton build on their ominous benchmark?
Until the final few hours of Friday's afternoon session there was little to separate Mercedes and Ferrari, nor was there any reason to suggest the world champions had extended their 2017 advantage over their chief rivals.

But while it can be unwise to read too much into testing, Lewis Hamilton's 1:19.333 was too quick not to acknowledge. The fastest time of week one was set on the medium tyre - which may yet have been the optimum compound in the cooler conditions - and was just two tenths of a second slower than the Briton's 2017 pole time in Barcelona.

The Mercedes team seem a lot happier than they were this time last year, when Ferrari had made a considerable jump in performance - encouraged by their W09 and confident it can keep its predecessor's title-winning speed and power while eradicating its "diva" traits.

Hamilton's lap was, however, also posted so late into the week that Ferrari seemed to choose not to respond. And though Sebastian Vettel said Mercedes were favourites to build on their recent dominance in 2018, one suspects the Scuderia have a lot more potential of their own to eek out this week.

F1 ready for its next test

Who has the most left in their locker? We'll soon find out. The championship hasn't even started yet, but Test Two could be crucial as both teams battle for early supremacy.

Are Red Bull closer to their rivals than last year?
Red Bull were the early pacesetters last week thanks to Daniel Ricciardo's Day One exploits but while the RB14 certainly looks to be an improvement on the underdeveloped RB13 from this stage last year, it remains to be seen whether the four-time world champions have really closed the gap to Mercedes and Ferrari.

A lack of consecutive runs on a dryer Day Four explains why Max Verstappen couldn't improve on his team-mate's benchmark, with the Dutchman insisting that "looking at lap times now doesn't make sense", However, there are still concerns over whether Red Bull's aero package compares favourably to Ferrari's, and if Renault have significantly closed the engine power gap to Mercedes, as hoped.

What's more, Red Bull completed 100 laps fewer than Mercedes during the first week, with Verstappen's Friday exit onto the gravel hardly ideal.

Still, this is a team that finished 2017 with two victories from the final five races, and there is cautious optimism around Red Bull that they can compete for more victories.

"I'm not too worried yet," added Verstappen. "You know that Mercedes and Ferrari are going to be strong anyway but I'm quite happy with the car so far.

"In the second week maybe we'll show a bit more, how we're comparing against those two teams."

And now we wait and see.

Can McLaren really challenge the top three?
Their Honda engine may have improved towards the end of last season and is now showing promising signs of aiding Toro Rosso but, judging by the timesheets at least, McLaren would appear to be the most improved team of 2018 as they prepare for a second week of testing with new partners Renault.

Indeed, they've gone from being almost three seconds behind the fastest time after the first week of 2017 to just 0.5s adrift, while Stoffel Vandoorne set the third quickest time of the week.

But before McLaren fans start dreaming of podiums, one must consider just how much disarray Honda were in last year, as well as the fact that Vandoorne's lap was set on the quickest hypersoft tyre, and at the best time of the week.

Considering that, it's probably more likely for McLaren to be battling the likes of Renault rather than challenging Red Bull and the rest when it comes to Australia.

"We are not aiming to be winter world champions," a hopeful team principal Eric Boullier told Sky Sports. "We are just looking at our programme - and that has gone well."

Challenging the elite may just be too great an ask this year but or the first time since 2014, there is a belief that McLaren can at least compete again heading into Test Two - where we should get plenty more pointers about their progress.

What is the midfield pecking order?
Now here's where it gets really competitive. Including McLaren and the steadily improving and deep-pocketed Renault, there are arguments for nearly every team on the grid to believe they can challenge for consistent Q3s and top 10s.

Haas, perhaps surprisingly, finished as the fifth fastest team and Kevin Magnussen's Day Four lap - which was the quickest of the week on supersofts - has given the US outfit the perfect springboard for Test Two and beyond.

Williams seem to have prepared a more aerodynamically-efficient car this year, with technical guru Paddy Lowe overseeing their off-season work for the first time. Their first week was encouraging rather than inspiring, but with an up-to-date and improved Mercedes engine at their disposal, they can never be ruled out. There are also question marks over whether reserve driver Robert Kubica is in fact the fastest man in their otherwise young stable.

Toro Rosso enjoyed a remarkably steady and impressive first week as they started their Honda partnership. Finishing on top of the mileage charts and without a failure of any sort, technical chief James Key is already hopeful of matching Renault power by mid-season. Lap times appear to be the only cause for concern, but Honda - despite their obvious short-comings since returning to F1 with McLaren three years ago - have proved before that they can improve over a season.

Force India, fourth-place finishers in the previous two seasons and incredibly consistent, have hardly given away anything when it comes to their VJM11's potential, finishing bottom of the mileage charts and as the second slowest team. With Sergio Perez and Esteban Ocon set to get more running this week after just a day each in Test One, expect the boys in pink to go surging up the grid.

And even Sauber, while still some way away from looking like genuine contenders, have enjoyed a positive start to the season. Aggressive new livery, aggressive new car, aggressive new Ferrari engine.

As were only halfway through the winter testing programme, it promises to be a fascinating week, and we should get a lot more clues into the midfield pecking order.

And will we see more laps?
An important question after the chilly weather and unexpected snow severely limited teams' progress last week, and the answer should be a resounding yes.

The forecast for the upcoming week in Barcelona looks much more promising, with temperatures expected to average out at around 16 degrees celsius over the four days. That's positively boiling after Test One.

The increase in track temperature should result in far more running - despite fewer engine failures, teams have completed 600 fewer laps compared to this stage last year - and quicker times, to boot.

Now let's get it started!

Sky Sports F1 is the only place to watch every Formula 1 Grand Prix, qualifying and practice session live in 2018. Get Sky Sports F1.