Everytime you join a server, you download the files including models. These gets stored in your gmod folder. So I doubt it's TDM Car addons causing the issue. Sometimes, missing player models can be result of conflicting models that gmod is reading (which means you gotta delete the conflicting ones). Sometimes, the issue is with the model itself. And so on.I had this problem too about a two weeks ago. And console getting spammed about missing player models. Restarting game/PC didn't work. But when i removed all my workshop content from my game and and unsubbed all content (I only had TDM Car addons) the player models suddenly worked again as they should, but i don't understand how TDM Cars can affect player models.