What Williams learned from Kubica's test

Robert Kubica was one of the best of his generation, a potential Formula 1 world champion, whose hopes of realising that expectation appeared scuppered when he suffered life-threatening injuries in a rally accident.

Even he thought a return was "nearly impossible". But he has kept that dream alive, and now, after testing F1 machinery this year, a return to the grid with Williams is within his grasp.

You will be hard pressed to find someone who does not want to see Kubica back on the grid. It's a story for the romantics. But Williams is not allowing itself to get whisked away.

It is insisting performance is what counts. And it was not prepared to rely on testimony from Renault, which gave the Pole a series of runs as part of its own evaluations earlier this year.

That's why Williams chose to run Kubica in a 2014 car, at two very different circuits - Silverstone and the Hungaroring, before trying him out in 2017 machinery at the Pirelli test after the season finale. And Williams is in no rush, and under no pressure, to decide quickly.

The team is risk averse. It wants to be thorough, but it knows there are certain things it will not be able to find out until Kubica contests a grand prix weekend, such as how he will cope in a racing situation. But there are several things it can find out.

First on its checklist in Abu Dhabi was to eliminate any doubt about his fitness. It was evident after Kubica ran in the 2017 Renault in Hungary that doing a full day took its toll on him. That is understandable considering the latest generation of F1 cars are far more physically demanding to drive. His return to contemporary F1 machinery was a full day, under immense pressure, and he completed 142 laps on a demanding track.

In the two 2014 Williams tests, it became clear that his fitness had improved, as he was gradually ramping up a demanding training regime. But to be certain, Williams wanted to run him in a 2017 car. He completed 100 laps over the course of six hours at Yas Marina on the first day and the team was very pleased - leading Williams chief technical officer Paddy Lowe to say there are no concerns that Kubica's injuries will affect his ability to race in Formula 1.

Kubica said on Tuesday that he felt physically stronger than in 2010. It's one thing to say it, quite another to be able to demonstrate it - but it was noticeable in his demeanour afterwards that his fitness had improved dramatically. He wasn't as visibly tired as he was at the Hungaroring. That's one very important item ticked off.

When he drove the 2017 Williams, he was unable to make any changes to the car, because it had to remain in the state it was raced last weekend to adhere to the strict rules for tyre testing

The series of tests have also proved that very little adaptation to the car is necessary. On the steering wheel, only minor changes have been made. And even then, all drivers have a slightly different set-up on the wheel. All the cars have the option to enable push or pull shift and Kubica prefers that method with one hand rather than changing gear using both hands. The team also ran a modified headrest, which features an indent on the right-hand side (pictured below) to give him a fraction more space to rotate his arm.

Another thing on the checklist was consistency. There have been claims Kubica has been unable to deliver a series of consecutive lap times in the same ballpark. But each test has been for a different purpose, in different conditions, with different machinery. It is not as if he has embarked on a bespoke testing programme in current machinery, aimed at building him up and allowing him to make the adjustments himself.

When he ran in the 2012 Lotus, it was a specification of car he was roughly familiar with, but well out of date. The 2017 Renault was at the other end of the spectrum, and while the focus was to evaluate his capability to return, he also had a job to do for Renault, working through the team's regular test programme.

The tests in the 2014 Williams were with a new team, in an old car, and way off the physicality of 2017. When he drove the 2017 Williams, he was unable to make any changes to the car, because it had to remain in the state it was raced last weekend to adhere to the strict rules for tyre testing. The programme, too, was dictated by Pirelli.

However, taking the penultimate 14-lap run on Tuesday, he completed three laps straight out of the box that were near identical 1m44.0s. He followed that up with seven laps that were between 1m44.1s and 1m44.4s. He completed the stint with two laps in the 1m44.7s.

Williams has plenty of data to analyse and will do so over the coming weeks, so a decision is not expected imminently. It can compare Kubica's data with that of Lance Stroll and Sergey Sirotkin from the test, but it is complex as they were all running different programmes. There are also comparisons to be made with other cars on track during the test and the running over the course of the Abu Dhabi Grand Prix weekend, but again, the same caveats apply.

Williams will have also wanted to get an idea of Kubica's performance and the early signs are that it is inconclusive. "It's a really complicated topic, performance and speed, so to read a timesheet is quite misleading," said Lowe.

On Wednesday, he focused on shorter runs and tried the ultra-soft and hyper-soft tyre compounds. He did five runs of four timed laps, with a quick lap followed by a cool down lap. He then ended the day with a one-timed-lap run on the hyper-soft, which was his quickest of the test, 1.934s off the pace. However, it is believed he was still not pushing for the ultimate lap time, but working to a specific programme, so it's difficult to get a read on his ultimate pace.

While Lowe repeatedly said the test was focused on gathering tyre data, it did represent an opportunity to see Kubica's potential and progress. The team was impressed by how quickly he got up to speed.

"Robert is not super-human," said Lowe. "He doesn't know the car, he doesn't know the tyres. He doesn't even know the circuit very well. So it took a bit of time. As we know from the race weekend, the tyres are very difficult to bring in to temperature. Especially the harder ones you're starting the programme with, as naturally you'd do. So it's actually quite a difficult process to really hit it on the out lap and being ready for Turn 1. But he did a good job considering those challenges."

Tyres were another focus. Even the current drivers, who have raced the new generation of tyres all season, are struggling to get them into the right window. Kubica has never raced on F1 Pirellis and had minimal running on them in restrictive testing conditions, so he was keen to get more time evaluating the different compounds.

It is understood he felt a breakthrough was made at Yas Marina with his understanding of them, and while he needs more running on them, he has the confidence that he can get on top of it with time.

"My experience gives me a comfort zone that if things are going well there shouldn't be bad surprises" Robert Kubica

His confidence, not just with the tyres but in general, is a factor in Williams's decision, too. Kubica says he wouldn't come back and sign a deal if he didn't feel he could deliver when it counts. On several occasions over the last few years, he admitted a return to F1 was unlikely, close to impossible even. But he has been a man transformed in the last 12 months.

He has embarked on a demanding physical programme in a brutally determined manner, and it's paid off to the extent where he now not only feels that he is capable of returning but that he can do it at a high level.

His competitive nature is such that he wouldn't be interested in coming back if he didn't believe he had the capability any more to win. Williams also needed to know Kubica believed he could do it. After all, talks started with an element of doubt in the minds on both sides. The 2014 tests moved to eradicate some of that and the 2017 test helped, too.

Kubica is wary of the threat posed by Sirotkin. The Russian brings a strong financial package and showed good pace in the Abu Dhabi test. But the way he answered a question on this topic spoke volumes about the confidence his performances in the 2017 car have given him.

"Sergey is a very good driver and he has done a very good job," he said. "He's very talented and he's probably one of the drivers who deserves a chance. But I'm looking more at my feelings and somehow my experience gives me a comfort zone that if things are going well there shouldn't be bad surprises.

"I'm having a bit different priorities and it will take a bit of time but I'm more looking for myself than looking for references and I think if I get the chance, the chance to be fast is Australia, not here."

The Abu Dhabi test gave the mechanics a chance to work with Kubica properly. Valtteri Bottas's departure was a tough one to take because he was usually at the limit of the car's capabilities. So they knew that whatever the result, that was the level of performance they had delivered from endless days of hard work. The team is craving that again as it would boost morale. Recruiting Kubica, providing the team believed he had the potential, would do that job.

It is understood the mechanics and engineers warmed to him instantly. They were impressed by the way he gelled quickly with the team around him and built up a good rapport. It felt like he had long been part of the team. They also loved his attitude.

On Monday before the test, he spent hours with the team preparing for his running, focusing on the minute details before his track walk. On Tuesday, he was in bright and early and even after he had finished running, he didn't want any downtime.

Instead he wanted to get into the garage and keep an eye on how Stroll was getting on. Then on Wednesday, he focused on what Sirotkin was up to, before getting in the car and diligently working through his own programme at the end of the day. The quality of his feedback had been one of the standout factors throughout the 2014 tests and he confirmed that again when driving the 2017 car.

The Kubica test went well. He proved his fitness, slotted in well with the team, delivered brilliant feedback and did everything that was asked of him during the programme. However, while Williams believes there is more to come from Kubica, questions remain over whether he can achieve that potential and if so, how long it will take to achieve that.

Ahead of the race weekend, there was a feeling Kubica was the man for them and after his running on Tuesday, that was only enhanced. But Sirotkin had a strong day when he stepped in. Admittedly, he is more used to the 2017 cars after his FP1 running for Renault, but nonetheless in a new team, his ability to get on the pace quickly got people thinking. Kubica's few hours of running on the second day was solid, but not spectacular.

Right now, it looks like Kubica has the edge, but Sirotkin is very much in the game for the race seat - and at the very least a reserve role with an eye on the future. To complicate the situation, it has emerged Daniil Kvyat, despite not testing for the team in Abu Dhabi, has become a very strong contender for the race seat.

Williams reserve driver Paul di Resta is still an option, but the Scot has drifted to fourth in the pecking order with Pascal Wehrlein now considered to be a long shot, and expected to return to the DTM with Mercedes.

Williams now has some thinking to do. The plan is to go back to the factory and crunch the data. It is hoped a decision can be reached before Christmas but there is scope to delay until the new year.