Audi and Porsche have found a way to improve airflow over their rear wings at Le Mans, it has emerged. During the official pre race test day both the Audi R18’s and Porsche 919’s ran with interesting two part rear wing end plates which feature shaped and angled leading edges. Additionally the Porsche design also features a three dimensional outer section. When first spotted there were mutterings of the designs being ‘clearly illegal’ and ‘I don’t see any way that they can comply with the rules.’

Looking at photographs of the end plates in question and comparing them to article 3.6.2 of the 2015 LMP1 technical regulations it does seem that indeed both the Audi and Porsche designs are illegal. 3.6.2 states that the end plates, must have a minimum constant thickness of 10 mm, must have edges rounded with a minimum constant radius of 5 mm, the surfaces shall be flat and parallel to the vertical plane passing through the longitudinal centre line of the car, and that Apart from the fixations to the bodywork permitted above, no bodywork elements must be attached onto the end plates. Two part end plates are specifically allowed.



The two parts of the Porsche design are clear to see here (above) with the leading edge sitting at a slight angle and having a totally different section. Looking from the side you can see how this changes the overall design of the endplate (below)



Audi’s layout (below) is neater with the forward piece flush with the rear piece, it is also more sculpted than that of the Porsche.



It is clear that some parts of both the Porsche and Audi designs are not flat and parallel to the centre line of the car (vertical plane). Indeed they are clearly not. So how is this legal, well according to Chris Reinke head of the LMP programme at Audi Sport the leading edges are intact not endplates at all “If you look closely you will see that those parts are not attached, they are bodywork and so are not part of the endplate at all.”

But even this is hard to fathom, as the rules (3.4.1) clearly state that “All bodywork behind the rear axle centreline and more than 200mm above the reference plane must form a smooth, continuous, unbroken surface without cuts, and be visible from above the car with the rear wing removed.” Both Porsche and Audi insist that if you look really closely it is possible to see that the design complies with this rule too. The designs do indeed seem to comply with the letter of the rules, although certainly not the spirit of them.



However with this said a close inspection of the Audi endplate from above shows that actually the endplate (the flat rear section seen here – left side of the picture) has an overlapped section with the ‘bodywork’ forward part. With the ‘bodywork’ removed the exposed leading edge of the end plate would not be ‘flat and parallel’ as it would clearly be stepped.

The ACO & FIA have inspected both cars and seem happy with the solutions on display, though official pre race technical inspections have yet to take place. Rear wing and rear bodywork design is a particularly touchy subject for LMP1 manufacturers after Porsche was found to have illegal bodywork at last years test, and Toyota’s innovative rotating wing was exposed during the race but deemed legal (and later banned).

Nissan and Toyota are not using the concept on their wings, and a rumour inside the paddock claims that the reason that both Porsche and Audi have the concept at the same time is that staff have gone from one to the other taking information with them. It is not clear which brand thought it up first!



One Porsche did line up for the pre test group photo with an illegal engine cover fitted. On the black 919 the rear deck extended beyond the rear edge of the diffuser by a few mm. This was likely just a fit and finish issue rather than any attempt to cheat. When on track the issue appeared to have been fixed.

