The key question Ferrari hasn't answered positively

Only one thing has been consistent about Ferrari's season, and that's the peaky nature of its performance. Having left pre-season testing as favourites in the eyes even of Mercedes, the SF90 has only shown that kind of pace throughout one weekend, Bahrain, and even then other problems conspired to cost it victory.

Coming to Barcelona, the big question was could Ferrari recapture it's testing form? With the accelerated introduction of its new-specification engine, as well as aerodynamic upgrades including a modified front wing, rear endplate tweaks and an elongated engine cover fin, there is hope of a step forward.

But perhaps more significant than that question is that, regardless of whether it's faster or slower than the Mercedes, does it feel like it did pre-season? This was something Vettel was keen to discover.

"Obviously, the car was really good in testing," said Vettel on Thursday. "We arrived in Australia and we struggled a little bit to feel the same. I think the first four races for us have been a little bit up-and-down. There were stretches where the cars felt really good and other parts where the car hasn't - but deep down we know that the car is strong. So, we are trying to put the bits together and trying to understand.

"We haven't found the silver bullet - but in the last 10 years I never found the silver bullet so I don't think it exists. It's really getting down to the detail, trying to understand more and more, trying to understand the conditions that we face, and trying to obviously improve and make sure it doesn't happen again.

"Now, this weekend will be interesting for us because obviously we had such a good feeling and it's not so long ago. I'm pretty sure I remember how the car felt and it will be interesting to see how it behaves the next couple of days. But I'm quite confident if we can get to that level then we should be very competitive."

Even by Friday standards, we should be cautious. Ferrari has been marginally more aggressive with its engine on Fridays in 2019, but with a new spec introduced teams are generally a little more conservative

The feel of the car is all-important because it will indicate firstly if Ferrari is on top of the tyres here, as well as whether it has mastered the set-up peculiarities both of its car and the modified aero regulations.

This is what makes it a significant test for Ferrari. Given engine upgrades usually produce the biggest single performance steps, it's doubly so as this should be an opportunity to attack before Mercedes responds with its own scheduled power unit step.

To go back to the question of pace relative to Mercedes, the evidence of Friday is that Ferrari is behind. To that we must add all the usual caveats that Friday practice can be misleading, fuel loads vary and engine modes differ and progress will be made overnight, but there's no sudden bounce back for Ferrari as yet.

The deficit to Mercedes was three-tenths, a significant part of that in the slower first sector, as championship leader Valtteri Bottas set the pace.

Single-lap pace

1 Mercedes (Bottas), 1m17.284s
2 Ferrari (Leclerc), 1m17.585s
3 Red Bull (Verstappen), 1m18.035s
4 Haas (Grosjean), 1m18.153s
5 McLaren (Sainz), 1m18.658s
6 Toro Rosso (Kvyat), 1m18.722s
7 Alfa Romeo (Raikkonen), 1m18.727s
8 Racing Point (Stroll), 1m18.839s
9 Renault (Hulkenberg), 1m18.861s
10 Williams (Russell), 1m20.191s

Even by Friday standards, we perhaps must be cautious with this. Ferrari has been marginally more aggressive with its engine in Friday practice this year, but with a new specification introduced teams will generally be a little more conservative with the way it is used.

The long-run pace also puts Ferrari behind, and by an increased margin. Counting six laps on softs to normalise things across different run lengths, with anomalous laps discounted, the deficit increases to 0.468 seconds. Both Charles Leclerc and Vettel put in very similar pace on their long runs, albeit with the latter running a lot further, suggesting the intra-team battle should be another Ferrari talking point this weekend.

Long-run pace

1 Mercedes (Bottas), 1m22.592s
2 Ferrari (Leclerc), 1m23.060s
3 Red Bull (Verstappen), 1m23.129s
4 Toro Rosso (Albon), 1m23.297s
5 McLaren (Sainz), 1m23.483s
6 Renault (Ricciardo), 1m23.552s
7 Haas (Grosjean), 1m23.915s
8 Racing Point (Perez), 1m23.967s
9 Alfa Romeo (Giovinazzi), 1m24.422s
10 Williams (Russell), 1m25.519s

It was also a strong start to the weekend for Bottas, who was fastest in both sessions and shaded Hamilton on long-run pace. Hamilton appeared to struggle a little more with the car balance, with his style of turning in more aggressively on the brakes to rotate the rear seemingly asking a little too much of the grip at times. But he also pointed to variable wind conditions, which could also have played a part.

Bottas, by contrast, looked from trackside to be loading up the rear a little more progressively and got more out of it. Of course, given this is Friday and the track will continue to gain grip, as well as Hamilton's set-up being honed, none of this means this is necessarily going to be a Bottas weekend. But it's at least a strong start for him, even if he did lose track time in FP1 to an oil leak.

There was no evidence that Mercedes is anything other than favourite. But the question of how much more is to come from the Ferrari engine at least suggests things could change

Bottas also pointed to the improvements made in the feel of the car since pre-season testing. This perhaps isn't a surprise, as Mercedes ran it's genuine 2019 aero package only at the second test having done the first with a far earlier, baseline, version and was still working to get the best out of it.

"The car felt really good today, completely different to how it was in winter testing, and it seems like our cornering performance has improved," said Bottas. "The balance around the lap is also better, so it looks like we've taken the right direction since the winter."

One driver who doesn't feel that the direction, in terms of feel at least, has been right since the winter is Vettel. While he talked up the engine and aero upgrades, he answered the question about whether or not the car is giving him what he wants negatively.

"The car is obviously a step forward, we've been putting quite some pieces on the car and quite some performance on the car," said Vettel after FP2.

"In terms of feeling, that's what I struggle with. I had a very good impression at the first week of testing, not so good after that."

While Ferrari has been very strong on straightline performance this year, it has also been at its best in fast corners. But the slower turns have been a problem, and this still is the case at Barcelona. The Mercedes does excel on turn in to the slower corners, and at times both cars looked strong through the chicane on Friday morning. This will be the area where Ferrari focuses most intently on making inroads. And although there's no significant dynamic issue that's obvious from trackside, it only needs to be a slight deficit to add up to a significant time gap.

So the final verdict is that there was no evidence on Friday that Mercedes is anything other than favourite for its fourth pole position in five 2019 grands prix. But the question marks over how much more there is to come from the Ferrari engine at least promises things could change, and the relative pace of the two teams did seem a little out of kilter with what we've seen on Fridays so far.

As for which Ferrari driver will lead the charge for Maranello, that remains up in the air.

But Leclerc has found the car less difficult than Vettel at times this year, and given he was the faster Ferrari driver today it could be another significant weekend in the battle for supremacy in the team.