Banked turns... Your car is narrower... Should we be worried?
On another subject, why all this talk about airfoils? You don't have airfoils... you have a 3-dimensional body. There's a quote in the article about the Laval team that said a similar thing. This sounds like an over-simplification. I'm all in favour of useful simplifications for the sake or making clear decisions, but this one sounds misleading. Let me just make my point carefully so that I can reassure myself that I'm not going off half-cocked on the subject:
Looking down on the car body you have illustrated, I can easily tell that the rounded nose, curved sides and tapered tail make it look like the cross-section of a typical airfoil. At a guess it could be a NACA 0015 or something similar with the greatest thickness at about 30% chord. This sounds like a rational starting point for selecting the overall shape of the body, following which will come the refinements to fit driver, chassis, wheels, fairings, vents and so on.
Where there seems to be a problem is when I read statements like "...lower airfoil profiles with lower drag coefficients..." That raised a flag when I read it in the Laval team article, but I assumed the journalist just won't understand these finer details. But I'm going to pin you down on this for discussion.
A body like your car's, which is a long slender object, will incur considerable amounts of profile drag, but more than that, it will have parasitic drag due to surface texture and irregularities, fairing interfaces, and varying amounts of induced drag from the vortex shed in cross-wind, such as the one I can see in the graphic above. Each wheel fairing also sheds a vortex. Has a sum of all these factors been done that gives you confidence that the profile drag rules them all?
Taking the point further, all the charts you find in books and XFOIL and UIUC are done on 2-dimensional models, which implies zero span-wise flow. I don't think you can make that assumption. Not even as a rough starting point. And the reference area (wing cross-section) is different from frontal area of the car you use. If you have, in fact, selected an airfoil shape for the planform shape of the car, and have reproduced that shape faithfully around the entire perimeter of the car, then can you model a zero-degree angle of attack case and arrive at the same pressure and velocity distribution published in the book? It would surprise me if you could.
So maybe I'm not interpreting the direction you take correctly, when making comparisons: When you model the entire car, and run CFD simulations, do you only refer to the frontal area for Cd or do you also use the cross-sectional area in the horizontal plane, too?
If I had a 3 meter wide wind tunnel I'd love to put your car from last year inside it and try validating all the CFD you did on it!
No kidding you can get lift on the car body in a crosswind. Short "stubby" wings are excellent for generating lift at very high angles of attack, especially when they are adjacent to walls, which is the ground in your car's case. On the upper side of a 2D airfoil, the flow would separate at 25 degrees, but on your car the cross-flow can just circulate from windward side to leeward side, thereby reattaching some of the flow to the leeward side of the car. Stall delayed. (This just repeats what I was going on about above, I just realized).
The Laval team may speak and work in french (though not necessarily), so the term "Turning force" may be a lost translation of "Lateral force" or it may mean "Drag during turns". Hard to know for sure which way to take it. Sounds most reasonable to assume they have tabulated the forces in each of the 3 axes: One longitudinal drag, one laterally, one vertically. The effect of the lateral force may cause it to turn, but that may depend on where the centroid of the distributed load is applied...
(sorry... gone on and on haven't I?)
