Who will be leading the way when the teams hit the track in Spain
Trying to pick up speed in Formula 1 is a bit like trying to lose weight.
If you are massively overweight, the first few kilos are quite easy to lose but then it just gets harder and harder.
It is the same in F1 - if you are massively off the pace, it is easier to find big improvements in your car than if you are already quick.
In Barcelona on Sunday we will find out which teams are most likely to be in good shape for the rest of the season.
The cars have been in the field since the first race in Melbourne, so it has been a bit hand to mouth for everyone - the early-season long-haul races are a very tough phase to try to introduce anything new to the cars.
So the first European Grand Prix is a natural fit to roll out the next big wave of development and performance items for all the teams.
The teams are like boxers at the moment - everyone is saying how awesome their new aerodynamic package is going to be - and that is to be expected.
But it is easy to talk the talk. We will see on Sunday which teams can back it up on the track as well.
I don't expect BMW to turn up and win in Barcelona - they might take a good step, but they are not on the level they were last year
My Red Bull team have a few new aero bits but we have also been trying to drop a few smaller ones on the car while we have been away. We are trying to make the car as quick as possible every time it is on the track.
Everyone should still be on a pretty big learning curve with these new regulations; there is still a bit of low-hanging fruit around to develop these cars and make them a bit faster.
McLaren are a good example of that. They were clearly in massive trouble in the winter and still not great in Australia but they have made reasonable progress since then.
They started to improve in Bahrain and we will see how they go in Barcelona.
There is still a period now where people can put on quite a bit of pace and that could be between 0.25-0.5 seconds a lap, which is a lot.
Designing, making and running these new parts is a huge challenge for the factory and this year you have to try to understand them without any testing between the races, so Friday's practice sessions should be interesting.
Red Bull's top engineer Adrian Newey is a 'genius', Webber says
But I am not saying it is going to shake the grid up a huge amount - we have seen in the past that teams who struggle at the start find it difficult to make huge steps and come through.
There might be small changes throughout the pack but I don't expect BMW, for example, to turn up and win in Barcelona. They might take a good step but they are not on the level they were last year.
These new rules this year are pretty tight and you have only got a set area to work in. Eventually that area becomes even tighter because as you do more work, you find there are more restrictions in the avenues you can use to develop the car.
That is where you need to find yourself an engineering genius and luckily we have one at Red Bull. His name is Adrian Newey - our chief technical officer.
Adrian has an incredible knack of doing things that are before their time. That is what geniuses are like - they can see things that other people cannot see.
In the 1990s, he took the Williams and the McLaren cars on to another level and made racing incredibly boring in the process. The other cars looked pretty much prehistoric compared to some of the ones Adrian had designed.
He is very clever and he can dissect the rules down to work out how he can get the most out of the design from the nose right through to the rear of the car.
They say there are a lot of left-handed geniuses out there and Adrian Newey is certainly one of them
You can see that on the Red Bull, which is not only beautiful but it has some clever and innovative ideas on it as well.
Adrian is also incredibly competitive - that was one of the first things I noticed very early on with him.
You do not always see that level of competitiveness from geniuses or engineers at his level, you usually get it from the people on the front line like the drivers but he is just so bloody competitive as well, which is fantastic.
He is quite a quiet, diffident person when you first meet him so you probably would not expect him to have that passion in his belly but he does. It is the same passion he shows privately when he does his own racing in his historic racing cars - he is very driven.
Adrian has always got a pencil in his hand and he is very, very good with it. He will do a little drawing for you to show you a few things and he really makes it simple for you.
Obviously, he has to dull himself down a lot when he talks to us drivers! He is incredibly crafty - they say there are a lot of left-handed geniuses out there and he is certainly one of them.
He definitely found the right business to work in. It is very rare that his cars have not won races.
The Red Bull car is packed with lovely design details
There needs to be a bit more made about what Adrian has done as an individual because his cars have won the Indy 500, IndyCar championships and big sportscar races as well as so many F1 grands prix. He is a legendary car designer.
This year's Red Bull car is certainly the best-balanced F1 car I have driven, so that is a great start.
That control gives me and my team-mate Sebastian Vettel confidence to explore the limits of the car and no matter how quickly you go you still feel that you can find pace and improve in certain areas.
It is one of the best cars on the grid - that is because the packaging has been very well put together aerodynamically.
And the fact that we have been so quick without so far using one of the 'double-decker' diffusers that have caused so much controversy this year is testament to the fact that the concept is fantastic.
It will need to be because Barcelona is an incredibly tough circuit for the aerodynamics of an F1 car because the average speed is so high.
You need a very efficient car, which means good drag on the straights, but you also want to be very, very stable around the low speed corners.
It is a great track to test your aerodynamics and if the car is not working, if it is not balanced, the driver has got nowhere to hide.
Mark Webber was talking to Andrew Benson