Step 1: Extract the files from the WinRAR file to a folder you want to keep the files in!!
Step 2: Open your Gta V main folder.
Step 3: Go to Menyoostuff. (Make sure you have Menyoo installed!!)
Step 4: Then go to the Vehicle folder!
Step 5: Copy and paste (Ctrl + V) the files into to Vehicle folder and you are done!!!
Step 6: Enjoy the vehicles!!!!