In the final part of ESPN's look at Ferrari's 2015 season, we analyse the Italian team's chances of taking the fight to Mercedes in 2016.

Now the dust has settled on the final round of the season, Formula One's attention has shifted to 2016. In truth, the teams' factories have been focused on next season for several months, but with the on-track action over for another year, the news agenda is finally catching up. The main talking point is clear: will Ferrari be able to take the challenge to Mercedes in 2016?

It's rare that two rival teams will agree on anything in F1, but at the end of this season both Mercedes and Ferrari estimated they were level pegging on power. Both sides analyse GPS data and top speeds to measure each other's progress, so the fact they came to the same conclusion suggests their power outputs are as close as they have ever been since the start of the V6 turbo era in 2014.

"Sadly you never have the luxury of putting your power unit and their power unit on the same dyno and having a dyno-off to find out who's got the most and the way you judge the opposition's power is a little more imprecise than that," Ferrari technical director James Allison explained to ESPN. "You could see from space last year we were nowhere, but with the sort of methods you can use to analyse, you can see that in the battle of Mercedes versus Ferrari we are there or thereabouts this year.

"But it doesn't mean we are resting on our laurels they are not going to stay still and there is much more to be done. But the power unit team and technical partners of the power unit team have had a remarkable 12 months to drag Ferrari up by its bootstraps to get to where we are today."

Mercedes' power output has not stood still this year, so not only has Ferrari closed a gap of roughly 50 bhp that existed in 2014, it has also matched the moving target of Mercedes' own development. After two years of domination in 2014 and 2015, Mercedes team boss Toto Wolff admits his team is increasingly worried by the growing amount of red in its rear-view mirrors.

"Ferrari has made a big step from 2014 and considering the results we think that could well be the case for 2016. We take the Ferrari competition and threat very seriously. Competition is good and important for F1 for there to be more going on at the front. Ferrari is our best frenemy."

Many of the technical improvements Ferrari made this year were relatively low-hanging fruit. The mistakes of 2014 were easy to identify once testing got underway, but due to the FIA's freeze on engine development they could only be rectified for the start of 2015. Reproducing a similar step in performance over the coming winter will not be so easy.

What's more, the early signs suggest Mercedes will make a big step of its own in 2016. Rather than chase out-and-out horsepower in a season it had already sewn up, Mercedes' big in-season upgrade at the Italian Grand Prix was targeted at creating a prototype engine for 2016. The upgrade still brought performance, but its full force will not be felt until the opening round in Australia next March.

In order just to remain in touch next year, Ferrari must make sure the wave of development that carried it back to winning ways in 2015 continues to offer performance in 2016. Allison is confident there is still enough unlocked potential in the regulations to do that, but admits it will be tougher than last year.

"I think the regulations are still relatively young, the power units are already really impressive things, but the regulations are young and there is more to be had," he explained. "I think it was more straightforward last year because once we had figured out where the gain was at, it was easier for us to correct our error, but us, Mercedes, Renault and Honda are all working with a young set of regulations where there is opportunity.

"Our competition is certainly not going to be resting and I hope that we are not either. I hope that we can make steps next year, not only in our own absolute power -- that much is guaranteed -- but also in the hunger and skill of our people that will be enough to stick our noses in front."

Patrik Lundin/Sutton Images

Although the first test is still over two months away, Ferrari has made its targets for 2016 clear. Team principal Maurizio Arrivabene did not hold back in a recent press briefing, telling reporters "If you want my honest expectation, it is not to be closer to Mercedes but to be in front of them". Race driver Kimi Raikkonen says the early numbers from the factory look promising, but is not willing to read too much into them until the car hits the track.

"If you think what we have done from last year to this year, then we are going to make another step next year," he says. "I have 100% trust in everybody and we can see the numbers, but until we put the car on the circuit we will not really see where we are.

"And even if we are really happy and everything is like we expect, we don't know what the other side has done. Of course we are going to be stronger next year, but will it be good enough? Only time will tell."

But to focus too much on the engine would be a mistake. Ferrari may have matched Mercedes for power this year, but Raikkonen was still 0.814s off Nico Rosberg in the final qualifying session of the season in Abu Dhabi. Most of that gap appears to come from the chassis and aerodynamics. Allison says one of the biggest misconceptions around the current regulations is that Formula One has become an "engine formula".

"It's not an engine formula. You can say with absolute certainty it's more of an engine formula than it was at the end of the V8 era, because with frozen engines what could you do? But this formula that we enjoy today is much more like F1 used to be.

"Mercedes are not beating the other teams just because they have got some rocket ship engine, they have got a very good car. Ferrari has got the challenge of having to improve on all levels to beat them. The power unit is going to be a key part in that, but the chassis is also going to be a key part in that."

At this early stage Allison is not willing to give any more away about Ferrari's plans for 2016. Just like its rivals, the rest of us will have to wait until pre-season testing to see if all that hard work pays off.