Hi Matteo,
I downloaded both of your mods (I think 1998 Duffer mod is also partly yours).
Unfortunately I could not play it on both of my laptops:
Laptop 1:
Duffer's mod had firstly all white car (tex not correctly uploaded). When I read this forum, I adjusted graphics to max. Fortunately it helped, although I still have some problems with GP4 crashing in Melbourne and when reloading session in tv view. Logs indicate left and right mirrors failed to upload.
But your mod fails differently, I still have default 2001 textures.
Laptop 2:
Duffer's mod has white cars under all graphic options. None of them helped.
Unfortunately I cannot play with textures like in old good times (I haven't touched GP4 since 2008). Back then I just opened cars.wad with EasyWad, uploaded there carshapes and textures. If it didn't work, I just resized them, restarted the game, and it was ok. Now with CSM it's a black box, you don't see where carshapes and textures are stored.
I suspect that my laptops are not powerful enough (I mean screen resolution), so there are no appropriate textures for my resolution. Again, if I knew, I would resize them and re-uploaded.
P.S. Mirror problem occurs on every car for example by passing start/finish line in Melbourne. So it's not a particular car.
P.P.S. I also developed performance files for 1998, now fine-tuning them.