Where the Ferrari F1-75 and the Mercedes W13 were already vastly different beast when it came to sidepod design, their 2023 contenders are even more contrasting.

Taking a quick look at the way they have approached the airbox and engine cover design it is clear that Ferrari's SF-23 has a very slim, triangular airbox that rapidly converges in the flat, black vertical panel required to meet the minimum surface regulations. The bodywork at the back is so closely packaged that you can virtually follow the exhaust lines.

Mercedes on the other hand have retained a fairly large air inlet above the drivers head, meaning both teams continue on their own development paths. It's also clear that the car's "shoulders", the bulges that extend from the halo pylons towards the back are very elaborate and uniquely feature a wedge to guide airflow towards the back of the car.

The big difference for the sidepods here is that on the Mercedes there is a huge gap that allows airflow to pass around the sidepods and through the rear suspension elements onto the top of the diffuser. The Ferrari on the other hand likely has more components positioned lower down to the ground for a lower centre of gravity while aerodynamically relying more on flow over the sidepods. And what to think about the rear wing efficiency that is likely negatively on the Mercedes...

Time will tell which one is better. One could argue though that Ferrari's approach - a continuation of their 2022 concept - already proved its worth.

Also note in the picture the difference between the single pylon rear wing support and the double pylons and Ferrari's series of winglets around the airbox.

A clear trend that has been going on even before the current set of regulations is for teams to move components closer towards the car's centreline. This trade-off has everything to do with an attempt to aerodynamically optimise the sidepods. Since most teams now agree the latter need to feature a downward slope towards the rear, components needs to be put elsewhere.

Alpine's A523 is no different and also follows the 2023 trend of further enlarging the car's shoulders to guide hot air to the back of the car.

In addition to cooling louvers - also known as shark gills - on the sides of the shoulders the A523 also has apertures on the ridge of the engine cover. For Alpine this is a continuation of a design route that they've followed for years. For more than several seasons now the Alpine cars feature a relatively bulky airbox that houses a channel to feed the engine while also having channels to cool a nearly horizontally positions central cooler.

Ferrari typically opt for the other extreme with a very slim airbox and they have continued to do so with their new Ferrari SF-23.

Mercedes's F1 W13 car at today's Bahrain pre-season test turned out to be a different beast compared to what the team tested at Barcelona two weeks ago. The team have made it a tradition to use an early version of the development to test first before introducing the latest and greatest aerodynamic developments in the final test before the season kicks off. Eyes turned when the car was revealed with a major development of the sidepods and floor.

Though the BCN iteration already featured narrow and compact sidepods, the inlet was high up and the upper side impact structure nicely integrated into the sidepod body. This new version however has a narrow and high cooling inlet, wider at the bottom than at the top. This means there is no real undercut on the sidepods, but instead a slanted surface that allowed Mercedes engineers to package components low to the floor and closer to the car's centreline, something that theoretically helps the car's dynamics.

The side impact structure is now also completely detached from the sidepod, allow air to flow underneath it and still over and around the sidepod surface. It is now basically a separate wing that provides home for the mandatory crash structure and is a support for the wing mirrors and some vertical winglets on the upper surface. This particular design feature raised some eyebrows early on with Red Bull Team Principal Christian Horner saying 30mins after seeing the car that some features "don't follow the spirit of the rules".

Further back, the same "narrow" philosophy is used, and just like in BCN, the engine cover has a high shoulder line but is very narrow top to bottom, quite similar to what the Mercedes-powered Williams team are doing.

Along with the sidepod update, Mercedes have added a fence on the outer side of the floor channels, trying to fend off the turbulence coming off the front wheels. The wavy edge of the floor, something that features uniquely on the BCN W13, is now gone.

We truly are nearing the no-sidepod F1 car...

Red Bull Racing have once again produced a very interesting car with its RB18, a car that was well hidden until it his the track today at Barcelona. Apart from its particular sidepod shape, the rear end boasts some significant details in an uncharacteristically high downforce set-up, especially compared to what Ferrari is testing on day 1 at Barcelona.

The RB18 for instance features sidepods that slope down, creating a ramp for airflow to continue over the diffuser. While some other teams have focused more on the coke bottle shape to get the rear of the sidepods narrow, Red Bull made them as low as possible, aside from the central tunnel that most teams now also feature to cover centrally mounted components and create a host air outlet around the exhaust pipe.

In Red Bull's case, this central funnel covers the rear suspension elements, with the image showing the rockers that actuate the push rod - after many years of Red Bulls with rear pull rod suspension layouts. This did make packaging the exhaust a bit complicated, leaving Red Bull to curl the exhaust pipe up, from underneath these suspension components, through the bridge that support the single central rear wing pillar into the mandatory straight final 150mm of the pipe.

Left and right of the exhaust pipe are the flaps that form the beam wing. As other teams have opted for two stacked elements (at Ferrari the lower elements continues underneath the exhaust pipe), Red Bull has the left and right flap separate, connecting to the rear impact structure. Unique in this design is the second flap that is unusually big and has a sinuous trailing edge, quite clearly to help the diffuser work efficiently. Surely other teams who might have missed this will already be looking into the possible advantages of this solution, and perhaps also planning a copy for their own cars.

Finally it's interesting to note the brake duct exits that blow how air and brake dust upward. This was previously expelled through the rims outboard but is no longer possible in the new regulations as they mandate inlet and outlet to be on the inside of the wheel, with no airflow through the wheels at all.

Ferrari have gone radical in their approach to this year's F1 75 contender, not least by the design of their sidepods that are very unlike anything else seen so far. A dented upper surface and a flat sidewall are its most intricate details that quickly triggered the aerodynamicists' interest. To validate Ferrari's approach and stop guessing in the dark, forum and F1T team member Vanja#66 made a new car model and ran some CFD analysis, with surprising results!

It is clear that Ferrari's concept is an entire package of design features working together, rather than simply a dent, or channel, in the upper surface of the car. Compared to the reference model that we ran here before, generated downforce and induced drag is changed all over the car.

Please check out Vanja's post in the forum that highlights exactly where downforce is gained, and how Ferrari have managed to cut drag at the same time.

Lots of people were stunned by Alpine's decision to fix a bulky airbox on the A521, but the team have already run their new car today with a new, more compact design that sees the rear end of the car considerably slimmed down. Along with the airbox that now tapers down more more quickly, the sidepod air outlets are smaller, leaving a lot more room low above the car's floor for clean airflow.

As the image shows, Alpine were focusing on front end aero on Friday morning with a rake fitted in the front wheel's wake. Today, with the updated rear bodywork, a rake was fitted at the back of the car as Alonso made his debut with the A521. Along with the update, the mid-wing was also ditched. It remains to be seen if this is temporary as the team is evaluating different configurations.

The update however doesn't change anything about the obvious design decisions that were made at Enstone. As confirmed by Alpine's Technical Director Marcin Budkowski on Saturday morning, the team opted to fit more components in the airbox area to be able to slim down the sidepods in an attempt to reduce downforce losses as a result of the narrowed floor.

“It’s a technical choice,” he said. “We found that slimming the sidepods was a positive direction, which is nothing new really. So we’ve repackaged and relocated some of the bulky things in the car and put them behind the air inlet.

“Yes, it gives a fairly spectacularly bulky shape on the car, but we found it works for us.”

Of course, no gain is for free, and Budkowski concedes there were a few compromises to be made.

“There are centre of gravity compromises but usually the aero performance wins over weight and centre of gravity."

Overall, this is a continuation of the design direction that was already overly obvious on the Renault R.S.20, resulting this year in smaller sidepod air inlets - the outboard top edges have been more rounded - and a very "natural" shape of the sidepods in general.

Mercedes's secrecy about their car's floor triggered the interest of many ahead of winter testing. Though the team were perhaps most clear about it, others similarly tried to not reveal too much about the floors, as this area is where teams had to adapt their designs to comply with the modified regulations without losing too much downforce.

The reduced floor width towards the rear wheels meant teams had to redesign an aerodynamic area that is crucial for the efficiency of the diffuser and management of airflow around the rear wheels. Mercedes for instance have opted to curve the edge of the floor up just in front of the rear wheels, while a set of three covered vertical vanes attempt to guide air outboard. Red Bull Racing's RB16B on the other hand has a vertical standing element with a curved leading edge just ahead of the rear wheel.

Another interesting difference is a fairly large standing vane further upstream on the Red Bull, just ahead of the cutout in the floor that is therefore hidden in the image. Mercedes have a similar cutout, but without a vane in front of it.

Bigger differences are visible when we look a bit closer towards the car's centreline. The marked pull rod for instance has a completely different mounting on both cars. On the Mercedes, this rod is positioned so it's mostly within the car's bodywork, while Red Bull stuck with a rod that is completely exposed to airflow. Most teams are following Mercedes in that design, but Red Bull's layout has the rear damper sitting further forward, allowing to declutter the back of the car.

It's also interesting to see that underneath the lower wishbones - which Red Bull repositioned further backward for aerodynamic purposes, the height of the Mercedes diffuser does not appear maximized. Instead, it appears to taper off towards the rear wheels. That's a first, as teams typically maximise volume in the diffuser, while Mercedes now seem to find more performance with a different design route.

The car's sidepod bodywork is also very different. Mercedes has some bumps and an undercut in the sidepods' surface while at Red Bull they maintained the very elegant bulbous sidepods with extreme narrowing towards the back of the car. This, along with fairly high sidepod bodywork at the back created a very open rear end to optimise airflow over the diffuser on each side of the gearbox.

At Mercedes designers have opted for narrower outlets, a Y-lon to support the rear wing, a mid-wing and a clearly more compact rear part of the airbox.

Time will tell who did the best job this winter, but it's good we continue to see quite different design philosophies.

Even though most teams still use the S-ducts, even when featuring narrow nose likes like on the Renault RS20 or Mercedes W11, it seems like McLaren will once again opt against an S-duct. Last year, with the introduction of the MCL33 car, the team switched to a narrow nose, and at the same time ditched the S-duct. It might be less advantageous to have an S-duct with a narrow nose, but the most likely reason why McLaren opted against is to be able to package things closer, while still maintaining rigidity.

It's clear that everything sits very tight together, and that even if McLaren would introduce an S-duct, it would either mean a redesign of the monocoque - which is very unlikely - or an exit that sits well ahead of the front bulkhead. It would therefore be fully integrated into the nose cone.

Currently, McLaren's chassis does not provide any space or apertures for ducting air, with the vanity panel that covers the suspension elements sitting flat on the upper surface of the chassis.

Also note the extensions on the lower surface of the chassis; elements that will certainly help to easily fit a new nose cone if that would be necessary. To make things even simpler, McLaren have reversed the pin connections from nose cone to chassis, meaning that the pin is attached to the nose cone, and that the ratchet to fix the nose cone needs to fit into the chassis, rather than the nose - which may be easier for the mechanic, as another one might still be fiddling to get the nose box at its right position.

Alfa Romeo have maintained a similar front-end philosophy compared to what featured on its 2019 contender. While many other teams went for narrow noses, Alfa stuck with the regular, flat-top nose cone with apertures at the tip of the nose to feed the S-duct.

The picture shows how the new Alfa continues to feature a very wide S-duct outlet, almost the entire width of the nose cone and just a few centimeters in height.

Left and right of it are new winglets since the second test at Barcelona. It was actually Sauber that debuted this sort of winglets last year, but as other teams copied and optimised the design, Sauber's new winglets are now less aimed at extracting air out of the S-duct - like they previously did by pointing outward.

Also note the pins that extend forward out of the four corners of the tub. The nose cone will fit onto these four pins, and can then be attached with screws from the side to fix it.

The second week of pre-season testing at Barcelona saw Red Bull Racing bring a fairly considerable aerodynamic update to its RB16, featuring detail changes on the front wing and the diffuser. The most obvious change was however the change in the barge boards where the team have now joined Mercedes and Ferrari in having louvres as sidepod panels, instead of only vertical deflectors.

The new design, at least in this area, is very similar to that from Mercedes with a number of flaps pushing air outbound and upward, generating a wee bit of downforce. These louvres sit in between vertical deflectors that are mainly aimed at directing air backwards.

Apart from this, detail modifications were also made to the vertical deflectors close to the chassis, while the panel next to the sidepod's air inlet has gained a slit.

It's no surprise that this comes together with front wing changes, as that front wing generates the Y250 vortices, as well as influence airflow around the front wheels and into the wake behind them.