It’s all gone quiet on the Kubica front – Mark Hughes explains why 

What do we know about Robert Kubica’s situation after the desert dust has settled from his Abu Dhabi Williams test?

We know that his best low-fuel lap on the Wednesday (he tested Tuesday morning and Wednesday afternoon) was a 1min 39.4sec and that Felipe Massa qualified the car the previous Saturday with a 1min 38.5sec. But, as ever in F1, it’s a lot more complex than that.

Differences to consider are tyres, engine power, fuel levels, track temperatures.

Kubica did his long runs, fully fuelled up, on Tuesday morning on the 2018 ultra-soft (a tyre reckoned to be softer than the 2017 ultra on which Massa did his first race stint) and for the first 14 laps before Kubica pitted, he averaged 0.6sec faster than Massa’s equivalent laps. But how much was the 2018 tyre faster by than the ’17 version used by Massa? We don’t know. How fast was the track? It was hotter, and therefore probably a little slower than during the dusk of the race. How did they compare on power modes? The engine, towards the end of its life, was turned down significantly. The preliminary consensus from the long runs was that Kubica was competitively quick, probably quicker than Massa had been when all the adjustments are made.

Kubica wanted to make changes to the car but the team insisted on keeping it as it was on the day. For Wednesday they made the changes he requested – and it’s felt that Sergey Sirotkin benefitted from these changes when he made his long runs in the morning. One of these runs averaged out slightly quicker than Kubica’s. But how much of that came from the set-up changes? Though Kubica had averaged quicker than Massa, Sirotkin averaged quicker than both. Was that just more favourable circumstances or real? 

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For the afternoon Kubica tried the car on the new 2018 hyper-softs with low fuel. He made two runs. On the first of them he got traffic on his first flyer and overheated the tyre, went for a second attack lap but by which time he’d overheated the tyre. On his second attempt he did the 1min 39.4sec, which was, by all accounts, quite a scrappy lap that didn’t hook up the best of his mini sectors. The day before, Lance Stroll on a low fuel run did a 1min 39.5sec (the same time as he’d set in qualifying). So looking just at the headline figures, Stroll did the same time as in qualifying, when Massa was 1sec faster – whereas Kubica only shaded Stroll by 0.1sec. 

Kubica felt that by Wednesday the old engine was giving no more power than the Renault he’d tried earlier in the year and that there was too much understeer in the car. Also, the hyper-soft was probably too soft for the circuit in that it required a lot of nursing in the first sector if it wasn’t to be overheating by the last few corners of sector three. The 2017 ultra, as used by Massa, was probably a faster tyre over the lap. Does the tyre difference and engine power difference combined account for the 0.9sec deficit to Massa’s qualifying lap? Had Stroll found a significant chunk of personal performance after his under-performance in qualifying and the slower circumstances just happened to equalise out to the same lap time? We don’t know.

But it does look as if, for whatever reason, Kubica struggled to find the best way to use the tyre over one lap but that over a race run he was competitive. This would tally with suggestions in the paddock that in the Hungaroring test with the ’14 car, Paul di Resta went faster than Kubica on the low-fuel runs. Is Kubica’s one-lap struggle just missing mileage? Is there something about the tyre he just cannot adapt to? Is it just a trait of the hyper soft around a track that was too demanding for it? We can see what Paddy Lowe means when he says it’s complicated.

Is Kubica still the favourite for the drive? Probably (assuming the paperwork issues over payment structures and insurance repayment can be resolved). But ironically the Abu Dhabi test has probably given more questions than answers, making Williams’ decision even trickier.