The start of Formula 1's European season is traditionally the period where struggling teams declare that 'their season starts here', while those further up the grid either try and increase their advantage or maintain their current position. Here's what to look out for across the coming races.

Can Mercedes maintain its momentum – and which driver?

The 2014 season has been dominated so far by Mercedes, with their winning margin over the next non-Mercedes car being in excess of 20 seconds at every race. There’s little doubt that they will win the title barring a disaster, but the question is how much more progress can they make? They’re further along the learning curve than their engine rivals, but do they have a greater ultimate potential or will Renault and Ferrari eventually be able to catch up? This weekend’s race will also show whether Mercedes has completely solved their previous tyre woes. The Circuit de Barcelona-Catalunya is notoriously tough on tyres and Mercedes was horribly exposed in 2013 – while the aerodynamic nature of the track should also reveal the true handling capability of the W05. On the driver front, the big question is whether Nico Rosberg can take the fight to Lewis Hamilton. The German still leads the drivers’ championship but he’s been thoroughly outclassed by Hamilton across the past three events. Barcelona and Monaco were two circuits in 2013 when Rosberg had the better of Hamilton – if he can repeat his form from last year then we have a title battle on our hands.

Can the Bulls charge?

Red Bull has been conducting a sterling recovery job after their shambolic pre-season campaign and the RB10 is clearly a competent car. Complaints persist from the team about their lack of top speed, although part of that is surely down to their typically high-downforce set-up – which explains their pace through the second sector last time out in China. Daniel Ricciardo has held the upper hand over Sebastian Vettel over the past couple of races, so eyes will be on how quickly the reigning champion can get the RB10 to his liking. Team principal Christian Horner has admitted that Red Bull needs to take the fight to Mercedes now if they are to prevent their rivals from sauntering to the championship.

False hope of genuine promise for Ferrari?

The Spanish Grand Prix marks an entire year since Ferrari last claimed a race win – their longest drought in 20 years. Ferrari endured a miserable opening three races which led to Luca di Montezemolo speaking out against the direction of the sport and Stefano Domenicali falling on his sword. Fernando Alonso claimed a podium in China, but with Kimi Räikkönen struggling to eighth it’d be foolish to point to that result as a genuine breakthrough. There will be high expectations on Alonso’s shoulders at his home race this weekend, so if Ferrari is to recover from an abysmal start then a strong race is required. Another indifferent result will simply determine that 2014 is another write-off for the Scuderia.

Midfield scraps – time to kick on?

Grouping McLaren into a discussion about the midfield highlights their difficult season so far. Melbourne was a promising event but the situation has worsened as Jenson Button and Kevin Magnussen finished outside of the points in China. Both drivers blamed a lack of downforce allied to a lack of front end grip, which accelerated the graining phase with the tyres. Hotter temperatures should aid them in Spain, but the front-limited nature of the circuit could again pose problems. Force India sits a fine third in the championship and performed well at a track which was traditionally their nadir. The VJM07 is a fundamentally sound car, the question now is whether they can develop it well as teams with greater resources will be able to develop at a quicker rate. The inherent pace of the Williams FW36 has so far failed to yield Williams a strong result courtesy of misfortune and a mixture of team and driver errors. Which one of these three Mercedes-powered teams will make the break and elevate themselves in the championship? Force India currently has the momentum, but can they repel McLaren and Williams?

Will Sauber's diet propel them up the grid?

Sauber has endured a torrid start to 2014. A distant 11th and 12th place in Australia preceded a couple of double retirements due to mechanical failures and accidents, while Adrian Sutil made it a hat-trick of DNFs in China as Esteban Gutiérrez struggled to 16th. The car has not demonstrated any sort of pace but some of its issues have been down to its weight. For Spain Sauber has produced a lighter version of the C33 – and this should especially aid the tall Sutil. Sauber also promises that there will be a ‘major aerodynamic update’ coming in Spain and it’s something they urgently require if they are to trouble the points in 2014.

Green shoots of recovery for Lotus?

Lotus, who will pay tribute to Spanish Renaissance painter El Greco this weekend, has not scored a point in the last five races, their worst run since the Benetton days of 2001. But the team is on an upwards trajectory and would have finished in the top 10 had a gearbox problem not manifested itself in Romain Grosjean’s E22. They also maintain that their twin-tusk approach will reap rewards and having had three weeks to work on their performance – allied to massive improvements from Renault, which they felt gained them two seconds in China – Spain should be the first race on which to properly judge the Enstone based outfit. The first few races were a test session as both Grosjean and Pastor Maldonado struggled with the recalcitrant E22. If they continue their current momentum, both drivers should be in contention for points in Barcelona. They’ve had their nadir and this great team has a history of bouncing back from the apparent abyss.

Have the ‘new teams’ missed their chance?

It seems absurd that Caterham and Marussia are still regarded as the ‘new teams’ – this is their fifth season in the sport – but their stagnation means that many view them as a separate entity at the back of the grid. Both teams have made slight progress in 2014, with a couple of scraps with Sauber so far and threatening to make it to Q2 on occasion. The early part of the year was regarded as their golden chance to score a point simply by finishing, but the astounding progress made by teams resulted in a higher-than-expected finish rate. The question now is whether Caterham and Marussia can move up and challenge the midfield, or whether they’re once again consigned to scrapping among themselves.