If you are using the TDU Platinum mod, the registry fix rarely works because the mod changes how vehicles are called. You need to patch the TDU.cpe file.
(or later)
Note: You must do this every time you launch the game unless you use a shortcut modifier like cmd /c start "" /affinity 1 "C:\Path\To\TDU.exe" . Solution 3: The "Radial.cdb" Clear test drive unlimited invisible police cars fix