I've been downloading numerous mods from this site, but I keep finding a bunch that won't open, says that 7zip cannot open the file .rar as archive. Any help?

Hi, I'm new to replacing cars in GTA5. I got a couple to work properly, but the rest I've tried keep getting their models glitched, like major parts of the car are spinning as if they were wheels, doors opening from weird angles, and from a short distance, they revert to the Vanilla game models. I don't know what I did wrong, I followed all the tutorials and directions. Are all these models just bad? Because I've gone through about a dozen with the same problem, only finding 2 that work correctly. Any help is appreciated. Thank you.