Mercedes is seeking to understand why it suffered its first "disastrous" weekend of the 2025 Formula 1 season at Imola and to find a fix to a recurring limitation that just won't go away.
George Russell suffered an infuriating Emilia Romagna Grand Prix in which his Mercedes was so hobbled by tyre woes he felt as if his car was broken, while team-mate Kimi Antonelli was knocked out in Q2 and had his first F1 retirement on Sunday courtesy of a throttle deployment issue.
That marked the lowest point of Mercedes' season so far, one which hasn't delivered the step forward into title contention that it would have liked for the fourth ground-effect season.
It was "comfortably our most difficult grand prix of the season", according to team representative Bradley Lord.
Russell was reporting problems with his car even on the laps to the starting grid, but the team couldn't find anything wrong with it.
"That feeling continued for 60-odd laps after. We had absolutely zero pace, clearly a trend when it's hot - the track was really hot today," Russell said.
"When it's hot, we're nowhere; when it's cold, we're quick. That was the trend last year, the same trend this year. We need to try and solve that."
Russell does take some solace from the fact that other frontrunners have had similarly poor weekends this year (presumedly, he's excluding McLaren).
"I think the fact is, every team has a disastrous race weekend at some point," Russell said on Sunday.
"This is our first one of the season. Red Bull had a disastrous one in Bahrain. This is our sort of first one of the year.
"Of course I'm not very happy - but your car isn't going to be podium-position week in, week out. That's what we've been doing recently, there's no excuses, it's just the reality of F1.
"You have all these different tracks, different tyre compounds, different temperatures. But it was definitely very underwhelming."
The upgrade question mark
Imola marked the debut of Mercedes' first big upgrade of 2025 - front suspension leg fairings with a notable McLaren-like upward flick, a new front wing and a reprofiled rear engine cover.
Russell qualified third on Saturday, only 0.137 seconds off Oscar Piastri's pole position - and he could have been on pole without a sluggish exit out of Rivazza - but it's not been Mercedes' one-lap speed that has been the problem in 2025.
It has routinely seen its gap to the weekend pacesetter (usually McLaren but Red Bull at Imola) balloon between Saturday and Sunday.
Mercedes wants to understand whether the new upgrades may have contributed to its worst race of the season so far.
"We brought a new front wing here because the new front wing is more performant than the old wing, we want to bring performance to the car as quickly as possible," Lord said when asked why Mercedes didn't just wait for Barcelona to bring it when the more stringent tests are introduced in a fortnight.
"In terms of feedback on the upgrades it's been relatively transparent through the weekend, now with the race data, we need to go back through that and understand what has been the effect of the different things we've changed, if any of that has in any way potentially triggered a worsening of the race pace.
"We don't think so at this stage, but we need to be open-minded given that we weren't competitive this afternoon [the race], so that will be something we're looking at, then making the relevant decisions on that."
A lingering limitation
Mercedes doesn't have much of a problem firing up its tyres for a single lap - Russell has a stronger average qualifying record than Lando Norris this season - but the management of its tyres over a race distance remains a lingering weakness.
It hurt it in 2024, and appears to have carried over into its 2025 car.
Imola was the most painful manifestation of that, with Russell's poor tyre wear plainly clear in the first stint when he went backwards from third on the grid.
But Mercedes was aware that the limitation was lingering this year too, as on Friday at Imola deputy technical director Simone Resta admitted it hadn't been resolved.
"I don't think necessarily that there's been an improvement in terms of tyre management," Resta said.
"There have been races where we were quite close. There have been races where we started with more, for example, the last one.
"So I can see a more generic pace improvement last year to this year, but nothing specific to the tyre management so far."
The upgrades brought to Imola were targeted at adding performance rather than solving this tyre weakness, so even though Mercedes can be competitive as in 2024 in cooler conditions or in low degradation races, what it experienced at Imola is likely to continue to be an issue in hot, high tyre deg races for the foreseeable future.
