I looked at the 'nap mod' physics.. "New Advanced Physics"..
Well.. I looked at the lateral tyre curve.. It isn't advanced there.. The grip peak is the same as 90% of all ISI curves, peaking at 6.2 degrees. If you look at the graph there is less dropoff which seems more right than most ISI curves, but calling that advanced is not right..
However, the curve has two peaks, which is strange..
However, the creator doesn't seem to understand how the lateral 'step' size works in ISI (it takes the SIN of the value) so the SIN can't be bigger than 1 (mathematic limit) ASIN 1 = 90 degrees and surely a lateral grip curve can't exceed 90 degrees.. you can't have 'more lateral angle' than 90 degrees, as that is as sideways as the tyre can work!
So what happens, if you translate the lateral curve to DEGREES, you see the peak at 6.2degs (as all isi sims, just about) then dropping to somewhere between 80 and 90% at 90 degrees slip... Now this second peak in the curve, happens way beyond 90 degrees slip and is thus disregarded by the sim as it can't take the SIN of >1!!
Now I ask you.. Someone makes 'new advanced' physics, somehow introducing a second peak in the lateral tyre curve, driving, and believing it is the best thing.... not knowing that this whole thing is disregarded as its beyond 90 degrees?? the A in NAP sounds more like Amateur..
The result is not that good either, its still ISI.. you can make it somewhat better with the grip curves that have less drop off but things are still weird. Snap back is VERY violent and the drive isn't convincing imo..
In the simracing / modding scene the quality of tracks and cars is graphically often substandard.. but the physics stuff is often far far worse! :/