David Coulthard previews the Spanish GP

Barcelona: the traditional start of the main European Formula 1 season. Where the real challenge begins in the fight for the world championship. So what did we learn from the opening four flyaways?

Those races told us, in terms of single-lap pace, that Red Bull has the fastest car. In terms of smart, sharp decisions by a racing driver, Jenson Button has been flawless. And in terms of someone suffering a luck allergy, Sebastian Vettel has the biggest right to feel aggrieved, given his three pole positions delivered only one grand prix victory.

Button: The king of cool

What a great boost for Jenson, to come back to Europe leading the championship like this time last year. He's definitely built upon his reputation, as it was one thing to win the world title by taking advantage of the fastest car, but it's a different level of credit and respect to win races in a car that wasn't the quickest in single-lap speed, but also in difficult conditions.

He's the king of the cool head, and proved his doubters wrong who said he'd be blown away by Lewis Hamilton at McLaren.

The other main talking point has been Michael Schumacher's pace. I believe he will be feeling a mixture of doubt and optimism heading into this weekend. Doubt, because things haven't work out relative to Nico Rosberg as he would have imagined. Optimism, as he will be looking forward to the upgrades Mercedes is bringing to Barcelona.

Upgrade or risk standing still

It would be a fairly mighty upgrade for someone to leapfrog Red Bull's single-lap advantage this weekend, but we did witness impressive progress from McLaren last year. Consider they started 2009 over 2s off the pace, and ended up winning races, those were pretty spectacular improvements that prove anything is possible.

Everyone's had the chance since the winter testing began to work hard back at base, look at other people's cars, optimise interpretations of the rules, and produce upgrades. Usually, from race to race, we see small tweaks, but this is a convenient juncture for teams to revise suspension, wheelbase, floor, top body, wings - all major parts with long lead times.

We've learned that Mercedes is lengthening the wheelbase of its W01. When you do that, it's not just the physical lengthening of the car that is the issue. There are many knock-on effects, such as weight distribution, centre of gravity, aero balance, etc.

We know that Michael loves that powerful front-end to his race car, and it's not looked like he's had that 'pointy' car to be aggressive and get stuck into it. Clearly the car is quicker in the hands of Rosberg - without ever looking like being quick enough to win - so let's see what the upgrade brings to Michael's party.

Can Alonso prance again?

It seems crazy to say it, but it does seem a long time since Fernando Alonso's victory in Bahrain. He will want a big result, not just because it's his home grand prix, and a track where he's traditionally been very strong, but because he wants to win a third world championship.

He will want Ferrari to deliver, like he does behind the wheel, and we've seen a chink in its armour with a recent spate of engine failures. At this stage of the season I wouldn't be too concerned about Ferrari's reliability in this department.

Given that the engines are blueprinted and FIA sealed, there is obviously an issue that's arisen since last year. It has to be a manufacturing issue, or a material fault, so because it's had reliability in the past with that motor, then surely it can regain it. It should be identifiable and therefore fixable.

He needs it to be sorted asap if he's going to challenge for the title this year.