Well done to S397 on a good release of the Endurance Pack.
As regards the cars, they seem to be well modeled graphically. Several issues have been pointed out already: M8 has poor internal rearview LCD panel resolution (may be intentional), misplaced wipers etc. But in general these look like minor fixes. I'd say the 'damage textures/shaders' are a little overdone especially on the M8. The sounds are good too, especially the 911, but I'll also say they cut off too early and you can't hear them from far enough away. That 911 in real life is ear-splitting as it goes past and you get the full blast of the exhaust in your direction, but its bloody loud from just about any distance - at COTA, pretty much the entire track distance.
On the physics front, the GTE cars are fairly benign and good fun to drive. However, we do need to discuss the 'new' tires. In the main, I'd say they communicate the road surface well, but they are still far too forgiving and willing to slide too much/too extreme slip angle. It's been this way for a while on most cars. Its particular noticeable on the Oreca though, and in particular the ploughing at the front. This latter may just be a poor 'out of the box' setup, but I think not. The front just doesn't have the grip it should. And when you watch the AI, they also have that terrible plough at the front, steering turned like 60-90 degrees, come completely off the power then the wheels straighten, and power is reapplied. We've had several of the past cars like this - the Radical most notably. I will say that when compared with the Endurance mod by Enduracers, the GT cars feel pretty good but the mod LMP2 cars are better although they are far too 'rubbery' in the suspension/tires. The S397 Oreca does not communicate the road surface and has lesser FFB when compared to the GT cars.
I think tweaks and fixes should be fairly easy to do, and overall I am impressed with the quality of this release.
However... its time, I think, to talk about general AI car behavior. This is far too 'digital' with the application of both throttle and brake, and nowhere near as smooth as a real driver would do. You can tell this by the sounds on throttle during a corner. Is there any hope for an improvement on these algorithms? I will however say the tires now don't often emit smoke from lockups every single corner like the older cars used to do/still do, not sure whether that is just a feature of the tire or the braking algorithm but suspect the former. There also needs to be a bit of adjustment to how the AI decides on a line to take when in multiclass traffic. Too often, the slower GT cars pull to the inside to try to block the much faster car; in fact, a GT car about to be passed would more normally keep to the regular line and let the faster car go past it offline, and would tend to give it more consideration on corner entry/braking rather than try to fight it off. Are there plans to address these issues?