The towing and storage charges occasioned by the impoundment of a motor vehicle pursuant to § 14-502 shall be and constitute a lien upon the impounded motor vehicle, except as provided in this section. If the hearing examiner finds pursuant to § 14-507 that the impoundment was improper and if he or she determines that the city shall bear part or all of the towing and storage charges, the lien created by this section shall be discharged. If the hearing examiner finds pursuant to § 14-506 that the impoundment was proper but that the towing and storage charges should be in an amount less than the amount of the lien, the lien created by this section shall be discharged to the extent that it exceeds the amount established by the hearing examiner. The holder of a lien created by this section may perfect such lien in any manner provided by law, but he or she may not retain possession of the motor vehicle when it has been released pursuant to § 14-506(a). In the event that the impounded motor vehicle is released from impoundment and the owner or his or her agent has provided security for payment of charges as required by § 14-506(b), the lien created by this section shall also be a lien against the security so provided, subject to being wholly or partially discharged as provided in this section.