It was an unsatisfactory end to pre-season testing for Robert Kubica who felt that Williams' last day of running in Barcelona had been thwarted by a car "not representative to what it should be".
Williams rolled out its FW42 two days late following a build-up delay, but once the Grove-based outfit got going its 2019 contender ran consistently albeit at the bottom of the pre-season pecking order.
Kubica racked up 90 laps on Friday, achieving his fastest lap in 1m18.993s, but was prevented from undertaking a performance run in the latter part of the day because of the FW42's degraded state and a lack of spare parts.
"We lost another day today," Kubica said. "Of course we did some laps, but the car's state was far from optimal.
"We had some issues. Unfortunately the car was not representative to what it should be, and this had a big impact on our test, our running programme of today.
"All the informations were misleading and in some way also was difficult to get any information for [the opening race in] Australia."
While the team had pulled out all the stops to minimize the FW42's build-up delay, the rush had inevitable repercussions in the end on pre-season testing.
"Of course I think we face a big delay, and some of today's issues is a consequence of being in a rush," added Kubica.
"If you struggle to have a car for the week before, you struggle to have spare parts.
"And unfortunately, today was required to have bits to replace, we couldn't replace them.
"In the end we did maximum from what we have, but this maximum is not enough, because in the end the car was from optimal."
Williams tech boss Paddy Lowe confirmed that the team had been forced to tweak its Friday afternoon programme - much to Kubica's desolation - because its FW42 was ultimately "too tired to continue".
"The long running in the afternoon was unfortunately brought to a halt because a number of critical bodywork parts had reached a stage of degradation that meant that we were no longer learning useful information from the car nor indeed for Robert," said Lowe.
"So we decided to switch our time to those final race procedural practices (starts, pit stops etc.) that we need to do before Australia.
"Having arrived late to the testing, our reliability during the running itself has been incredibly high. Up until today we were on track to complete our originally intended mileage and to consume all available tyre sets.
"But today this car has become ultimately too tired to continue.
"In the interest of saving our resources for the important racing in Australia we felt it was right to change the plan.
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