Under the skin of the Mercedes W04

Mercedes waited until the eve of pre-season testing at Jerez to launch the car with which it hopes to revive its fortunes.

A race win in 2012 should be seen as a sign of a good year, but Mercedes again struggled through another season of poor results with a difficult car.

Huge emphasis had been placed on developing the double DRS and the complex interlinked suspension, which left the car struggling with its tyres and lacking aero performance.

The past year has seen a massive investment in getting the 'right' people to run the team and Mercedes arrives at the first test with a breadth of experience to help its return to frontrunning pace.

But not surprisingly the new W04 bears a passing resemblance to the 2012 W03, with a tidier nose and a completely new sidepod/exhaust layout

The new car sets out to resolve its predecessor's aerodynamic and mechanical issues. Immediately obvious is a revised and slightly more conventional aero set-up. Crowning this will be a new front wing. The current wing still follows concepts first seen on the Brawn BGP001, whereas the new one will be a five element design and will appear later in testing this week.

Mercedes has reassessed its nose design

Above this is a revised nose. Last year's car had a rounded nose struggling to blend into the front of a rectangular chassis, so while Mercedes hasn't gone for a full modesty panel, the merging of the two shapes is now a little more streamlined.

One of the key features of recent Mercedes has been the cooling inlet behind the rollhoop. This year's roll structure is more conventional with exposed blades supporting the structure.

Mercedes has however left space for an inlet behind the rollhoop; this is expected to be used for a Lotus-style DRS device, tested last year after it was clear the double DRS would be banned for this year.

As the DRS device has to be passive and not operated by DRS or the driver, it's hard to get the airflow redirected to stall the rear wing when at high speed. It remains to be seen if a team can get a DRS device working effectively enough to be raced in 2013.

Evident on the 2012 car and even more aggressive this year are vertical vanes mounted to the front of the tea-tray splitter. These vanes start off a very complex aero set-up around the middle of the car.

Around the cockpit and above the sidepod fronts are little vortex generating fins, which direct airflow towards the exhaust exit to push the exhaust plume towards the diffuser.

Mercedes did adopt a Coanda-style exhaust in 2012, but this arrived late and never brought the step the team was looking for. On the W04 the exhaust exits in a McLaren style semi-Coanda set-up. The bulge from the sidepod features a short channel for the exhaust plume to attach to (hence semi-Coanda), and then the exhaust gasses pass openly over the floor to the diffuser.

The central section of the W04 © LAT

Unusually the bodywork is quite bulbous behind the exhaust outlet, as Mercedes seeks to vent the hot air from the radiators in an outlet formed by the bodywork around the gearbox.

The gearbox does not appear to be the low-line design rumored pre-season. Its carbon case is still neat and retains a similar pullrod operation.

Many teams employ passive hydraulic links between the front and rear suspension, to prevent the nose diving under braking in order to maintain the correct front ride height for the aerodynamics to work. But Mercedes has a more complex system that also replaces the anti-roll bars to provide set-up options for roll and warp stiffness. Team chairman Niki Lauda was critical of the system and it's not clear if it has been developed, simplified or removed.

Mercedes has opted for a 'semi-Coanda' solution

Whereas its rivals have oversized the rear wishbone to enclose the driveshaft, Mercedes has opted for a much slimmer profile and somehow still achieved the same effect.

Beneath all this complexity is the diffuser. Mercedes has altered its design from 2012, losing the small duct below the tail light and making the sides of the diffuser sweep out more aggressively to improve the expansion of air out from under the car for more downforce.

All these little step improvements show signs Mercedes is following convention and not trying to find a magic innovation to catch up to the pace of the leading teams. How the car evolves over the testing period, especially with a new front wing, will be important to watch.