Most of them are fully finished or close to finished, the only thing missing is LODs but no one bothers since you'll never see more than 10 cars in a private session and we all have beefy PCs anyway. All of them have custom physics and sounds too.

We just don't want to give out anything because:

you release the mod unlocked? it'll get edited and reuploaded with 1000hp and slick tyres the same day with altered/removed credits. (slivkasl JZA80, my old S14)

release the mod encrypted? people will shit on you for wanting to stop the above from happening and then eventually will rip the model and sell the parts for $40 (my FEED RX7, Dareks' Abflug Z32)

don't release? waaaaa waaaaa stupid fucking private modder you're so selfish stupid fuck

So as you can see there's fuck all incentive to give out anything and modders are sick and tired of it and have gone private due to people like the one you're replying to. Even RSS is sick and tired of it and stopped public projects.