[_Tommy]

Well yeah its possible, you will need here the OnPlayerEnterVehicle function.
Check what skin the player has - for example

pawn Код:

(if GetPlayerSkin(playerid) != copskin1 || if GetPlayerSkin(playerid) != copskin2) SendClientMessage(playerid, COLOR_RED, "You are not allowed to drive this vehicle"); RemovePlayerFromVehicle(vehicleid);

Find the cop skins you want and replace them with 'copskin1' and 'copskin2'.