So that's it then. The champagne has been sprayed, the lights have been turned off and Nico Rosberg has a shiny new World Drivers' Championship trophy to take back home to Monaco. But after the longest Formula One season in history - 21 energy-sapping races across five continents - there's no rest for the teams and engineers in the garages as they prepare for 2017 and its latest rule changes.

But what has 2016 taught us? Aside from debates over whether Rosberg is a worthy champion and if Hamilton was right to ignore team orders in his ultimately futile efforts to overhaul his teammate in the last race in Abu Dhabi, there's been a few key stories and tech developments this year on the engineering side.

Here are some of the key headlines and lessons that the 2016 F1 season taught us.

Power matters most...
At the end of the season, the results speak for themselves. Mercedes and their class-leading hybrid engine simply dominated. With Rosberg and Hamilton behind the wheel of the W07 car, they secured 19 wins out of 21, 20 of 21 pole positions, and eight one-two finishes, usually at a pace that the trailing Red Bulls and Ferraris just couldn't get close to.

A big part of that is Mercedes has the advantage of having indisputably the best engine on the grid. It's estimated the hybrid powertrain in the back of the Silver Arrows had an advantage of around 20 hp over its rivals - enough for a gap of nearly a second a lap on some circuits.

While second-placed constructor Red Bull have long placed a premium on aero performance to help in the corners, you have to catch the Mercedes first - and the rebadged Renault-powered team simply couldn't hold on along the straights.

...but so does reliability
Another simple fact is this - Hamilton won ten races to Rosberg's nine and won the qualifying battle by 12 poles to eight. Yet at the end of the day, it's the German that's going home with the title. One reason for this - though by no means the only one - is that even though their cars were mechanically identical, it was Rosberg who had the more reliable machine.

Whether this is down to the way they drive or pure luck, when Hamilton's engine blew up when leading the Malaysian Grand Prix, it was his third failure of the season, after problems prior to the races in China and Russia. As well as costing him in those races, the resulting penalties the Brit had to take in Belgium as a result of replacing those blown parts left him with simply too much to do to make up the gap.

It's therefore a clear illustration that you can have the fastest car in the world - but if it's not able to withstand the punishing schedule, it's not going to be enough.

Investment rewarded
With their second consecutive Drivers' and Constructors' Championship double, Mercedes continue to reap the rewards of a long-term investment programme that started long before the introduction of the new hybrid engine era. 

A few years ago, in the last days of the V8s, the team admitted they were essentially abandoning their current car's development in order to focus on the future, and this is a decision that's clearly paying off. It's also the result of a huge investment programme that's made Mercedes one of the best-funded teams on the grid, allowing them to keep developing 2016's car while also looking ahead to next season.

No resting on laurels
Further down the grid, there's evidence everywhere you look that the pace of development is as high as it's ever been, and no team can afford to stand still while their rivals are in a state of continuous development. McLaren, for instance, made significant steps forward from 2015's deeply disappointing season, with a car that was much more competitive.

Meanwhile, new entry Haas surprised many by finishing in the points in their very first race, though this early promise faded as the year went on and they couldn't keep pace with more experienced teams' development. Even at the very rear of the grid, perennial back-markers Manor scored points, as well as being much more competitive overall - it's no longer a foregone conclusion that they'll line up 21st and 22nd on the grid.

Farewell to legends
Finally, away from the technology side, 2016 also saw the sport bid farewell to three of its most popular drivers - two expected retirements that ended long careers and one that came out of the blue. 

Between them, Jenson Button and Felipe Massa notched up a total of 555 starts, 26 wins and one Drivers' Championship for Button (as well as one oh-so-nearly for Massa). Both had an association with Randstad's partner Williams - Button starting his career there back in 2000, and Massa ending his time in F1 with three seasons at the team from 2014 to 2016. They'll both be much-missed, and 2017's grid definitely won't be the same without them.

Given their long service, their retirements came as no surprise - unlike the third, that of Nico Rosberg, who shocked the F1 world with his announcement just days after winning the World Drivers' Championship at the age of 31. With a young family, and having achieved the goal he'd been working towards since he was six years old, its understandable why he'd want to walk away - but it certainly changes the dynamic for 2017.

Randstad has been the official partner of the Williams Martini Racing Team since 2006. The expertise, spirit of excellence and trust on which we base our relationships with clients and candidates are illustrated within the Williams Martini Racing team every day.

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