Aston Martin back in the game as Mercedes make key W16 change

Aston Martin introduced a sizeable update package for the AMR25 at the Emilia Romagna Grand Prix as they look to unlock the latent performance of their machine and improve their standing in the F1 2025 season.

The modifications include a major overhaul of the floor, underfloor and diffuser, whilst changes have also been made to the sidepods, engine cover and halo transition.

Aston Martin AMR25: Back to back

The team decided to test the two configurations back-to-back during free practice at Imola as they look for final confirmation of the difference in real world performance versus the results seen in their new wind tunnel facility.

This is especially important given they designed and tested the update in both the new and old tunnel, as explained by team principal Andy Cowell.

“It’s a package developed in a previous wind tunnel, but finally mapped in our new wind tunnel.

“So by the end of Friday evening, we’ll have track derived data, we’ll have new wind tunnel data and we’ll see how beautifully they overlay.”

The most obvious visual difference between the two configurations is to the shape of the sidepod bodywork, which could be seen during the back-to-back tests, with Stroll given the first taste of the new parts on his AMR25 (right), whilst Alonso ran with the older components.

The sidepod’s rump section has clearly been enlarged (see the added red lines, with the dotted line used as overlay), which alters how the airflow on the upper surface behaves, whilst the airflow’s behaviour along the flank will also be changed as the undercut and G-line have been fettled too.

The changes made to the edge wing will be almost indiscernible in this comparison but there’s been some modifications made to the rear, flatter portion of the surface, with the overarching horseshoe-style metal support brackets removed on the newer configuration too.

The geometry changes to that section of the edge wing are also indicative of the modifications that have been made to the floor’s edge beside and a consequence of the volumetric alterations made beneath the floor.

There’s also been a change to the diffuser, with the shape of the keel altered quite considerably, as the team have abandoned the rudder-style lower section (inset, arrowed) for a more traditional sloping transition.

This is obviously in combination with the changes, albeit out of view, that have been made to the underfloor’s geometry, whilst there’s also been alterations made to the fences at the front of the floor too.

To compliment the alterations that have been made to the sidepod and engine cover bodywork, Aston Martin have also adjusted the fairing around the rear leg of the halo, with the vertical vane (inset) that’s been stood on top of the assembly in the opening races discarded.

McLaren MCL39: Pool party

McLaren continue to use the same tactic this year as they did last, with parts arriving ahead of schedule in order that they can be tested in advance.

The arrival of a new, high-downforce rear wing and beam wing arrangement was announced by McLaren within the list of new components in the car presentation document.

But the team only had a brief dalliance with the setup during FP3 as they used that time to ensure these parts were working with the car as anticipated.

This is exactly what they did last season at this venue too, with their thinking also likely centred around having another option at their disposal if bad weather was to hit the circuit, which is obviously a relative unknown but with the parts available in the pool it might give them an advantage over their rivals if that did occur.

And given that the Monaco Grand Prix is just a week later in the schedule it seems prudent to have the option available, if time permits in the build schedule.

Mercedes W16: New is not always better

Mercedes introduced a number of new solutions at the Emilia Romagna Grand Prix including a new front wing assembly, alterations to the front suspension fairings and new engine cover bodywork.

However, whilst these were declared in the car presentation document ahead of the three days of running, one change made by the team could have slipped through the cracks, as it doesn’t have to be listed in the document…

The position of the upper, lead wishbone arm of the rear suspension was relocated for Imola, with the inboard pickup point moved down lower and closer to the lead arm of the lower wishbone.

Analysis: Emilia Romagna Grand Prix

? Imola GP conclusions: Verstappen’s Piastri lesson, McLaren’s fear, Tsunoda’s wobble

? Emilia Romagna GP driver ratings: A drop for Piastri with Verstappen perfect

The change will clearly have impact from both an aerodynamic and mechanical point of view, with the latter more about being able to trade some of their ability to get the tyres in the right window for qualifying, for a more stable operating window during the race, which has been an issue for Mercedes for some time now.

This is only exacerbated further when the track temperatures are higher on a race day when compared with qualifying, as noted by team representative Bradley Lord.

“The big limitation today was rear axle for us and rear overheating,” Lord told media including PlanetF1.com after the race at Imola.

“We have found ourselves front limited at some circuits so far this year, so we’ve got the challenge of the work this weekend has been on the rear axle and that’s been our big limitation. It’s clear.

“It felt like the gap between our qualifying pace and our race pace was, if anything, bigger this weekend and in the race today, rather than smaller, which obviously was the aim of the work that we’ve been doing.

“So lots for us to dig through and understand better in order to see where we’ve made improvements with the car and where potentially we’ve taken the wrong path.”

Read next: The Ferrari data that will give Hamilton and Leclerc reasons to be cheerful