...LED headlights are the first TO make their way to Le Mans.

It's been said elsewhere that Audi began using aluminum front diffusers on the R15 and that this practice had been continued on the R18. The reasoning was given that as a race wore on, the carbon diffusers were deteriorating, getting damaged, and front aero performance subsequently dropped off. Supposedly the car was very front aero sensitive. At first this didn't pass the sniff test at all. But with the R18 in all carbon, it is easy to differentiate between differing materials without a layer of paint covering it all up and indeed something is going on there. Posing a question, we get an answer. Yes, the front diffusers are made from a combination of machined aluminum with carbon skins (we can see at very least the top has a carbon skin, but the leading edge clearly appears to be aluminum and so too the mid section connecting joint). But the reason is actually quite simple and nothing to do with the durability of carbon, aluminum is particularly soft after all, especially in thin sections. With the diffuser's leading edge clearly aluminum, one can imagine the material is actually less than ideal from a durability standpoint; carbon at least has some elasticity.

Instead it's done because of very short lead times for aluminum and little tooling investment. In the end, Audi found that the cost of a carbon front diffuser was no different than the cost of an aluminum one. Weight or weight distribution wasn't an issue. That seems a little counterintuitive at first when everything on a race car appears to be scrutinized heavily for strength to weight and indeed it typically is. And one can imagine an aluminum front diffuser being heavier than an all-carbon version. But it's added weight in an area where Audi was already looking to put ballast (indeed, on most F1 cars the front wing is used as an area to place ballast--it's the lowest/furthest forward part of the car after all). But the big benefit was the ability to generate multiple variations and have them made very quickly for testing. To make a carbon part first requires a pattern to be machined. A mold is then laid up off that pattern, and then the part is laid up out of the mold. The process is labor intensive and time consuming and all your tooling is worthless if you decide to try another diffuser shape. Thus Audi saw aluminum as a way to actually reduce costs and decrease turnaround times.

Speaking of wind tunnels, Audi included this shot of the R18 undergoing full scale testing at Ingolstadt's Audi Wind Tunnel Center. What was interesting was not what was going on through the window, but what was behind the screens. At full resolution, you can clearly read the data off the computer monitors.
The data shows the drag coefficient, front coefficient of lift (.cl), and rear coefficient of lift. This would be .8486, -1.7965, and -1.5873 respectively. Initially we thought these were raw coefficients, but in hind site it appears they are CdX figures: that's the coefficient of drag (or lift, replace the 'd' with 'l') multiplied by the reference area. Thus the data needs solving for the raw coefficients to make better sense for us (well, for me really). Therefore we get a coefficient of drag (.cd) of .471 and a total coefficient of lift (.cl) of -1.8798. Assuming a frontal area of 1.8 m^2, that translates to 934 lbs drag and 3727 lbs. downforce for a L/D of 3.99:1. The balance is a very front biased 53% front. But let's also mention that given the nature of the Audi tunnel, spinning wheels, partial rolling belt, it doesn't have the ingredients to produce an accurate ground simulation and the numbers need to be taken with a grain of salt in that respect. Especially the balance.

Obviously this is one of two things: either a complete PR gaff or a deliberate release of information. If deliberate, then clearly designed for misinformation. It's hard enough to inquire about aerodynamics data from decades old race cars that have no relevance to current regulations or trends, thus there's little reason for Audi to release this information at this time.