Following a long off-season break, the 11 Formula 1 teams head into one of the shortest test periods, with just eight days of running this year to fine-tune their cars.
Although F1's regulations have remained relatively stable from 2015, there are a number of key questions that require answers ahead of the two, four-day runs, the first of which starts on Monday.
Line-up for first Barcelona F1 test set
Autosport assesses what lies ahead at Barcelona's Circuit de Catalunya.
1. IS THERE MORE TO COME FROM MERCEDES?
After dominating the past two seasons since the introduction of the 1.6-litre V6 turbo hybrid power units, there is surely nothing that can stop Mercedes' target of a three-peat this year.
But when you are seemingly at the top of your game, how do you raise it further?
Mercedes AMG High Performance powertrains managing director Andy Cowell only recently indicated there is more potential from a system that has helped the team win 32 of the last 38 grands prix.
Mercedes appears poised to stretch the boundaries beyond those they have already set.
2. WHAT TYPE OF CHALLENGE CAN FERRARI OFFER?
That's the million-dollar question.
Ferrari made a massive step from a low starting point last winter, but repeating the trick this year with its new SF16-H will be tougher.
The engine was its biggest strength last year, and a radical new concept - first rumoured towards the end of 2015 - might be what is needed to take the fight to Mercedes.
Although the SF-15T was one of the better cars at protecting its tyres, it struggled to switch them on and therefore excel in qualifying.
We will soon see if Ferrari has solved its tyre conundrum and made gains with engine and chassis development.
3. CAN McLAREN-HONDA RETURN TO THE FRONT AGAIN?
Honda's wretched performance on its return to Formula 1 last season was one of the major talking points, and all eyes will be on the Japanese manufacturer over the eight test days to see what improvements - if any - have been made.
It is understood Honda has changed the turbine, compressor and MGU-H, the latter proving to be a particular thorn in its side in 2015.
Reliability and an increase in speed are crucial if McLaren and Honda are to avoid a repeat of last season.
If nothing else, the body language of Jenson Button and Fernando Alonso at the end of their first days in the car will be a key indicator as to what might loom for this year.
4. HOW WILL THE NEW RENAULT WORKS TEAM GET ON?
Renault has asked for patience as it begins a new era in Formula 1, such was the protracted nature of its takeover of Lotus.
Starved of resources last term, Enstone now has the financial clout to fight at the front, but lacks the time before the start of the season to make up for lost ground.
Technical director Nick Chester admits the RS16 is a "compromise" given the late change of engine, from Mercedes back to the Renault power unit that has struggled for power.
Expect teething troubles early on, but this is only the start of a long-term plan.
5. WILL THE NOISE LEVEL IMPROVE?
Following complaints from fans and promoters alike about the lack of noise with the current engines, there is a new regulation that should help raise the decibels, even if still short of the old V8 era.
All cars must now possess separate exhaust pipes for the turbine and wastegate, whereas previously the latter simply fed into the turbine, stifling some of the sound.
Some teams have already released engine fire-up audio and there appears to be an improvement, but we won't know for sure until the cars hit the track.
Thankfully this is one of those questions that will be answered rather swiftly come the start of testing.
6. HAAS: MIDFIELD RUNNER OR BACKMARKER?
History says debutant teams do not fare well on their introduction to F1, yet Haas possesses all the hallmarks to suggest it could buck that trend.
Naturally dismissive of the phrase 'Ferrari B-team', Haas enters F1 with a Ferrari power unit and other parts from the Scuderia allowed under the regulations.
With two competent drivers at the wheel in Romain Grosjean and Esteban Gutierrez, the aim of achieving team principal Gunther Steiner's target of points this year may not be as romantic a notion as it sounds if solid foundations are laid in Barcelona.
7. WHERE WILL RED BULL SLOT INTO THE PECKING ORDER?
Red Bull had a torrid, winless season in 2015 dominated by rows over its engine supply that brought its future in F1 into question.
The team lives on with Renault power - albeit badged as TAG Heuer - and it will be hopeful of enhancing a chassis that ended last year as arguably the most capable on the grid.
Much will depend on Renault, which has set itself a target of halving the gap to its rivals over the course of this year.
Christian Horner expects to be beaten by Toro Rosso early, but if Renault achieves that, along with better reliability, Red Bull should pose a sterner threat.
8. WILL MANOR LOSE ITS BACK-OF-GRID STATUS?
For five years now, Manor has toiled at the rear of the field, never more so than last season, running an old car following its salvation from administration.
Owner Stephen Fitzpatrick is determined to push the team up the grid, and to that end has negotiated deals with Mercedes for a current power unit supply and Williams for a transmission.
While power will propel the team's cars closer to the midfield, it will only shake off its backmarker status if it has an aerodynamic package to match.
That is now the key.
9. HOW WILL THE ROOKIES PERFORM?
The 2016 F1 grid features rookies with impressive credentials in junior formulas.
Jolyon Palmer plans to "take a few more risks" after earning promotion to a race seat at Renault.
The 2014 GP2 champion only has a one-year deal and knows he must get up to speed quickly and perform consistently if he is to extend his stay.
Pascal Wehrlein became DTM's youngest champion last year and comes highly rated from Mercedes' junior programme, with Manor providing a good base at which to demonstrate his talent.
His team-mate, Rio Haryanto comes with lower expectations, but has won races in GP3 and GP2, including three last year in the latter.
10. CAN WILLIAMS MAKE IT THREE OUT OF THREE?
Williams faces a real battle to retain third in the constructors' championship for a third successive season.
The team made the most of a solid chassis and the class-leading Mercedes power unit in 2014, but found the going tougher in '15.
Performance chief Rob Smedley said Williams took some "strategic decisions" last season to begin work on 2016, and now we will see if that gamble has paid off.
Autosport will provide comprehensive live commentary and analysis from all eight days of pre-season F1 testing plus the team launches