If you extract the files direct to you "Gamedata"
Folder you will get some new(wrong) Folders in TC 65 and GTC 65 (65Corvette, the Daytonas get into the Shelby GT350 Folder.....)
So better you extract the Carpack to a new folder and copy the cars "by Hand" in your Team-Folders.
And maybe there are the same problems with the other carpacks. didn't checked it jet.