All 10 Formula 1 teams on track together for the first time for the opening day of pre-season testing gave us a lot to pour over.
From the first long-run comparisons of 2025 to trackside impressions of all 10 cars, here are nine key things we learned from day one in Bahrain.
How the top teams' times compared
More than a couple of hours into the first day of testing, last year's constructors' champion McLaren hadn't set a laptime. It was the only team in that position.
In trouble? Not according to McLaren, which insisted this was according to its original run plan. The team was apparently in no rush to rack up laps quickly after its initial runs with aero rakes attached to the car.
Once Oscar Piastri did reappear, McLaren was as busy or busier than any other team. Lando Norris followed a similar trend when he took over the car after the lunch break - and when he pushed, he was eventually very quick.
How consolidated does McLaren's early pre-season favourite status look? Headline times are of little value at this stage of testing but Norris was a couple of tenths clear of Red Bull and Mercedes, while Charles Leclerc's fourth-fastest time for Ferrari at around 0.4s off was probably not representative.
The spread is enough to be easily explained by fuel loads, engine modes, and the time of day that laptimes were set at.
Inevitably the top four teams from last year seem closely matched early on. But McLaren left the strongest initial impression.
How the top teams compared on track
If you had to pick a 'winner' based on the trackside eye test for the first day of running, it would be McLaren.
That's a disappointingly predictable pick given it topped the timesheets, but the fact is it looked the most composed and consistent car on track - particularly once Norris took over for the second half and was able to up the pace as the run plan allowed.
In particular, the strong traction on corner exit - key for Bahrain - suggests not only a good mechanical platform but also that the drivers are able to rotate the car well enough to ensure they aren't limited at corner exit.
Get more trackside analysis sooner in The Race Members' Club on Patreon - join now for 90% off your first month and extra updates direct from the F1 paddock
None of this means the other expected frontrunners should be written off. The Mercedes was probably the second-most-impressive car in terms of its balance and consistency, with both Kimi Antonelli and George Russell appearing confident in a car that has hit the track and worked well.
As for Ferrari, there were very promising signs although the fact that at times the car switched between responding well on turn in and picking up understeer with Lewis Hamilton at the wheel suggests there's some more work to be done on set-up. But there are hints that it could be a responsive, usable car once in the window.
The Red Bull looked assured while being driven at race-pace but did show signs of being somewhat tricky when on the limit. Liam Lawson perhaps struggled a little more with the car as the first session progressed, with a spin at Turn 3 the result.
Max Verstappen at times looked strong and consistent on long runs, but there was a run shortly before the power outage when he was attacking the Turn 10 left-hander and repeatedly failed to get the nose in as he wanted to, leading to time-sapping wide moments.
Whether that's last year's balance limitations rearing their head, or simply the consequence of an experimental run, remains to be seen but the question marks still hang over Red Bull's car.
What Red Bull's really up to
The launch photos and shakedown imagery were no mirage: the Red Bull RB21 really does look, and is, very similar to last year's RB20.
We made no secret of the fact we were curious what Red Bull was up to with a car we really thought would look more different when it finally hit the track.
But it hasn't sprung a surprise in Bahrain and the suggestion is that it won't by the time the season starts for real in Australia.
Red Bull is adamant that every aerodynamic surface has been tweaked or optimised in some way, but the visual differences amount to subtle things like a slightly reshaped sidepod, a change to the air intake below the airbox, winglets on the halo, a different engine cover shape and a revised beam wing.
This car is "fundamentally" what Red Bull will run at the start of the season, according to team boss Christian Horner, who effectively ruled out a major visual change when specifically asked about this by The Race's Edd Straw.
Why such a low-key evolution, then? Partly because Red Bull feels that despite its in-season downturn, the 2024 car was a solid platform. And didn't require a radical overhaul to get it back to its best.
Greater flexibility on the front wing will go hand-in-hand with changes we can and can't see, likely to the underfloor - and in fact, some TV images of the Red Bull showed the front wing upper elements bending a lot in Bahrain already.
Plus, we believe the lack of drastic visual changes is connected to Red Bull's wariness about using limited resources to develop a new or substantially different car concept for 2025, ahead of the major regulations changes coming for 2026.
How Hamilton's first real Ferrari test started
The bare laptimes tell a sobering story for Hamilton's first day in the Ferrari, with team-mate Charles Leclerc faster of the two and Hamilton himself a second slower in ninth - but this is testing, and such headline figures lack context.
In reality, the gap will not be so pronounced. Cool temperatures all day - unusually cool for Bahrain - meant there wouldn't have been the useful drastic shift in track conditions to favour those who drove later on. But Hamilton did drive at the slower time of day.
At times it all looked nice and connected. At others it seemed like a tricky first half-day in the 2025 car. Hamilton seemed to have a bit of pushback from the car when he tried to attack more.
He had a few notable wide moments at the low-speed Turns 8 and 10, and a couple of snaps exiting faster corners such as Turn 4. But, it's worth noting he never really stopped attacking, so there didn't seem to be signs of his confidence being sapped.
It's also possible that Ferrari had an understeery balance to correct for the second half of the day and maybe went too far in doing so, given Leclerc looked more rear-limited than anything else when he jumped in for the afternoon.
There is therefore no cause for alarm bells to ring. It speaks more to Hamilton starting on the back foot - which had to be expected given the scale of change, and which he has admitted himself - and facing a steep learning curve this week.
Lawson's instant impact
Liam Lawson hasn't had his first race for Red Bull yet, but the team is already in no doubt it's made the right decision by calling on him to replace Sergio Perez.
After embedding himself as much as possible with his 'new' team over the past few weeks, Lawson is said to have hugely impressed the crew that operates around him, with both his feedback and his attitude.
In an environment where first impressions count for a lot, Lawson's feedback has been praised by his engineers in particular, and it's already left the team convinced that progress can be accelerated as it builds up to the start of the new season.
After periods last year where Red Bull and Perez appeared lost in explaining why things were not working, and where trust appeared to break down as the RB20 became an increasingly difficult car and the constructors' championship was ceded to McLaren mainly thanks to Perez's poor form, having faith that both sides of the garage can contribute equally will surely feel like a breath of fresh air at Red Bull.
Caveated optimism for Mercedes' new era
The laptimes were encouraging for Mercedes duo George Russell and Kimi Antonelli, but perhaps more importantly the vibe from the team was one of optimism, even though it came with caveats.
Antonelli showed quite promptly in the morning that he has no intention of hanging about in learning the 2025 car, visibly pushing hard every time he started a run.
There were times where Antonelli looked a little scruffy driving the car - certainly coming past our team of experts standing trackside he was overdoing it repeatedly on the entry to the tricky downhill left-hander at Turn 10, and had a big lock-up at one point right in front of us.
But he was also quick, even though he was doing a lot of high-fuel work that boiled down to one run on lower fuel, and reported he was happy with the car's balance.
Russell felt much the same. He was among the fastest when he took over the car in the second part of the day and, again, relayed his satisfaction with what he felt from the W16 - calling it the best a Mercedes has ever felt around Bahrain.
The main asterisk against this is the unusually cool conditions. These have favoured Mercedes in the past - remember Russell's dominance in Las Vegas last year - and Russell admitted the team had to be "careful" because it's usually so much hotter here.
As he warned: "We don't want to get carried away with ourselves."
An early midfield leader?
There's a palpable sense of relief in Bahrain for Alpine, which is in a very different position to the horror show of 12 months ago when it floundered with an overweight and slow car.
Lead driver Pierre Gasly lapped comfortably inside the top six on day one, and although our technical expert Gary Anderson couldn't see a lot of difference between the new Alpine and the car the team finished last year with that's not necessarily a big drama considering how strongly Gasly in particular finished 2024 after the team's difficult start.
The only notable changes so far are a shallower sidepod inlet, more aggressive turning vanes on the floor and, as has been a common sight on the new cars of 2025, more anti-lift on the top wishbone forward leg on the rear suspension.
If Alpine is the early midfield leader - Aston Martin lost track time for a few reasons and was a hard team to judge - it is a very tight pack.
And different cars impressed on different metrics. For example, Alpine and Racing Bulls looked solid on track but the Williams showed signs of a touch of magic in this group.
While there were more moments where instability reared its head under braking, at its best it looked the liveliest of the chasing group.
What's Haas up to?
The slowest team on day one - by a mile - clearly wasn't on the same programme as others, which is something we saw Haas do last year too.
Haas conducted a lot of high-fuel running with rookie Ollie Bearman in the first half of the day, which Bearman said was tough to read because of his unfamiliarity with this track and the changeable wind conditions.
When the more experienced Esteban Ocon took over for the remainder of Wednesday, that long running continued. It was evident in the times.
Both drivers did report they feel this car is a step on what was driven last year. Bearman raced two grands prix for Haas while Ocon jumped in the 2024 car for the post-season test in Abu Dhabi.
How much of a step, though, is very unclear given such a drastic difference in run plan. The understeer we saw often plaguing the car trackside could easily be explained by the car being heavy, for example.
Hopefully the same goes for a contender for F1's actual slowest car: Sauber.
We've seen the Sauber properly for the first time now in testing but it remains an unremarkable evolution on the surface.
And it exhibited some corner entry and traction limitations that leave us with modest expectations for the soon-to-be Audi works team, at least for now.
Only interruption was a bizarre one
Wednesday's scheduled running from 10pm to 7pm local time didn't quite go to plan as an odd disruption meant the session had to finish at 8pm instead.
As is probably to be expected for the final year of a set of rules, all the teams arrived in Bahrain very well prepared with nobody obviously adopting the mantle of ‘team in trouble'.
Even McLaren, which started the day very slowly, easily racked up more than 100 laps. Only Aston Martin failed to hit triple digits - but there was no drama there that caused the day's only interruption, which was a bizarre one.
Shortly after 5pm local time, a power cut occurred. It plunged team garages, the paddock and the circuit into darkness as the sun set and the floodlights Bahrain usually relies on at the end of a testing day were extinguished.
It took the better part of an hour to fully resolve but the time lost was tacked onto the end of running so teams didn't really lose it - although we wonder, given how well every car ran, whether that extra hour was really needed.
