The champion has been known for some time, but the book officially closed on the 2015 Formula 1 season on Sunday at the Abu Dhabi Grand Prix. For the second straight year, Mercedes dominated the rest of the field and Lewis Hamilton took home the Drivers’ Championship. This time it was an even more comfortable win for Hamilton, as he earned an unassailable lead over teammate Nico Rosberg with three races remaining. But impressive form from Rosberg over the closing races and the stronger than expected performance of Ferrari over the course of the season means there is plenty of room for intrigue heading into the winter break.

Here’s a look at the season that was and what could lie ahead for Formula 1’s big names.

Lewis Hamilton

After edging a tense championship battle with Rosberg in 2014, Hamilton firmly had his teammate’s number this season. Victory in three of the first four races put him firmly in command of the title race, and a further seven victories, failing to finish in the top two on just three occasions all season, saw him wrap up his third championship in Austin, with 75 points still to play for. However, 2015 has not ended as smoothly as he would have liked. Rosberg won the last three races to take some of the gloss off of Hamilton’s year. And the relationship between the pair has continued to be fractious, with Hamilton making several complaints about team strategy in the final races. The problem has become such an issue that Mercedes boss Toto Wolff has even suggested they may have to drop one of their drivers in order to bring greater harmony. Reports have suggested that it is the champion who is most at risk, adding a significant backdrop to the title race in 2016.

Nico Rosberg

Having been beaten at the last by Hamilton in Mercedes’ first year of dominance, it was vital that Rosberg made an early statement in 2015 that he was ready to take the fight to his teammate. Instead, he allowed Hamilton to get in front, and even slipped behind Sebastian Vettel in the early going. But, while perhaps helped by a subtle shift in the setup of the Mercedes, the German came back fighting at the end of the season to claim, not only three consecutive victories, but pole position in the final six races. There is little doubt that Rosberg has the speed, but he now needs to show on a more consistent basis that he has the ruthless edge, particularly on race day, to come out on top. It is hard to imagine Mercedes’ huge advantage being completely wiped out in 2016, meaning the fight between Rosberg and Hamilton promises to be the center of the attention.

Sebastian Vettel Sebastian Vettel's victory in Malaysia provided plenty of optimism for Ferrari going forward. Photo: Getty Images

Sebastian Vettel

After a poor final year at Red Bull, the four-time world champion bounced back to prominence in 2015. A surprise victory in Malaysia in the second race of the season sparked excitement that Ferrari might just be able to contend with Mercedes. While that didn’t materialize, Vettel still exceeded expectations, garnering two more race wins and a total of 13 podiums. In terms of race pace, Vettel was able to get increasingly close to the Mercedes. Still there is still much to be done, especially in qualifying, where Ferrari remained a long way off the pace. Yet Vettel has spoken with confidence that Ferrari can take another step forward to take the battle to Mercedes in 2016, and, given how much they improved this year, Vettel could be a real factor in the championship battle.

Kimi Raikkonen

Vettel’s performance in 2015 was made to look all the more impressive by the efforts of his teammate. Raikkonen, nicknamed “the ice man,” has long been something of an enigma, giving very little away either on or off the track. But the appeal of the 2007 champion is decidedly on the wane after another year at Ferrari in which he was cast into the shadows by his teammate. Although Raikkonen claimed fourth in the drivers’ standings, he finished a full 138 points behind Vettel, and claimed a spot on the podium on just three occasions. Understandably Ferrari were thought to have given serious consideration to replacing the Finn in 2016. Although he was retained for another year, it appeared to be a decision based as much on a lack of outstanding alternatives as a vote of confidence for the incumbent. Now aged 36, Raikkonen will have to return to form strongly next year if he is to have a chance of retaining the seat for 2017.

Fernando Alonso In 2015, Fernando Alonso endured his worst season in Formula 1 since his very first year in the sport, in 2001. Photo: Getty Images

Fernando Alonso

The past season will not be one Alonso will want to dwell on for any length of time. Despite having long earned a reputation as the most gifted driver in Formula 1, the Spaniard’s team choices have left something to be desired. A double world champion with Renault in 2005 and 2006, he switched fruitlessly between McLaren, Renault, again, and Ferrari in the subsequent years. Last winter he made his most ill-conceived move yet, leaving the under-performing Ferrari to switched back to McLaren, right ahead of Ferrari’s return to form and McLaren, in a new partnership with Honda, enduring their worst season in more than 30 years. The team was embarrassingly off the pace in 2015, often failing to even make it past the first cut in qualifying. Finishing in the points for only two races and coming in 17th in the drivers’ championship will have been galling for Alonso, and it is little surprise that there have been suggestions he could even take a sabbatical next year. McLaren have spoken bullishly that they will be competing at the front of the grid in 2016, something they may have to provide concrete evidence of in testing simply to persuade Alonso not to sit the season out.