Miserable, horrible, baffling and inexcusable. Toto Wolff, the Mercedes team principal, had said he was lost for words to describe his team’s performance at the São Paulo Grand Prix, yet find them he did and they were a damning litany. Mercedes were left flailing at Interlagos in what was their worst performance of the season, but the real import goes beyond Brazil.

For the previous two races, in Austin and Mexico, the team had been decidedly upbeat. Their final major upgrade had delivered and indicated, Mercedes believed, they were on the way to understanding how to gain performance for next year’s car. In São Paulo that belief was battered.

Related: ‘Worst weekend’: Wolff wants change after ‘unacceptable’ Mercedes F1 display

On Sunday the W14 was a wilful, recalcitrant brute. Slow on the straight, slow though the corners and calamitous on the tyres. Lewis Hamilton finished eighth. He was passed with ease by the Alpine of Pierre Gasly and finished a minute behind winner Max Verstappen. His teammate George Russell was set to be lapped by Verstappen before he was spared the embarrassment when his car was retired with an engine issue.

Back in March, after the season-opener in Bahrain, an ashen-faced Wolff conceded that the team had pursued the wrong design concept and would be bringing in major changes mid-season. Since then they have acknowledged that next year’s car will be designed pursuing an entirely new direction.

The work on this year’s model was intended to improve it and, crucially, to feed into Mercedes’understanding of how best to maximise next year’s ride. The performance in Brazil raises serious questions about whether the team are achieving this at all and whether next year they can mount any kind of challenge.

With the car so fundamentally poor at Interlagos, where they won last year, Mercedes must consider whether there are still gaps in their understanding and interpretation of the current aerodynamic regulations such that they are still wildly varying from track to track. This does not for a winning car make. Red Bull, whose aero package is superlative, are strong in almost all conditions, and at every circuit.

That Mercedes remain at a loss at this stage of the season, with the new car long established, is clearly of concern. “It is baffling. From a really quick car, the best balanced and drivers happy, to a nightmare. How’s that even possible?” said Wolff. “What is it? What is it that’s not right?”

There was no expectation that the upgrades would turn the W14 from what Wolff described earlier in the season as “a nasty piece of work” into a race winner, but there was hope that it would at least provide a solid baseline from which to build. That baseline, it seems, is veering wildly and unhelpfully.

For the team that won eight constructors’ championships between 2014 and 2021 this is clearly inexplicable, but it has not come out of the blue. The car concept they brought to the grid in 2022 proved to be flawed. However, improvements to it during the season convinced those at the top of Mercedes that they were on the right track, such that they continued with it for this season. By the end of the first race Wolff acknowledged that was a mistake. But it was too late – they were committed.

This entire season has been a hangover from that and prompted the decision to start from scratch in 2024. “Fundamentally, we will have a different car next year and Sunday proves that is the right thing to do,” confirmed Wolff.

This is perhaps the toughest test Mercedes have faced since returning to the sport in 2010, but there may be reason for hope. The current car is flawed and so an imperfect test bed. Its performance is influenced by those limitations and, as Wolff noted, it was not a matter of ride height or wing settings that cost them in Brazil but basic mechanics. Whether the team have a handle on that for next year will decide their fate.

For Hamilton it was, he noted pointedly, a weekend to forget in a car he can not wait to see the back of. The 38-year-old has a contract for two more years with Mercedes but cautioned that he believes Red Bull might be not be caught. “The Red Bull is so far away that they are probably going to be very clear for the next couple of years,” said the seven-time champion.

Hamilton has never lacked motivation and there is no indication that he is any less committed to Mercedes. But he, too, expects more next year. His patience has been severely tested over the past two years; a repeat of Brazil in 2024 might stretch it to breaking point.