Whenever any vehicle, as defined in this subchapter, is used or intended for use to transport or in any manner to facilitate the transportation of any controlled substance in violation of subchapter IV of Chapter 47 of Title 16, it shall forthwith be seized and taken into custody by the peace officer or officers having knowledge of the facts of such use, but:
(1) No vehicle used by any person as a common carrier in the transaction of business as a common carrier is subject to forfeiture under this section unless it appears that the owner or other person in charge of the vehicle is a consenting party or privy to a violation of the Controlled Substances Act;
(2) No vehicle is subject to forfeiture under this section by reason of any act or omission established by the owner thereof to have been committed or omitted without the owner's knowledge or consent;
(3) A vehicle is not subject to forfeiture for a violation of §§ 4761(a) or (b), 4763, 4764 of Title 16; and
(4) A forfeiture of a vehicle encumbered by a bona fide security interest is subject to the interest of the secured party if the secured party neither had knowledge of nor consented to the act or omission.