(a) There is levied and shall be assessed and collected a car-sharing vehicle surcharge tax of 25 cents per half-hour, or any portion of a half-hour, that a rental motor vehicle is rented or leased by a car-sharing organization; provided that for each rental of six hours or more, the tax shall be assessed in a manner provided in section 251-2. The car-sharing vehicle surcharge tax shall be levied upon the car-sharing organization.
(b) An organization that qualifies as a car-sharing organization as defined in section 251-1, that is registered with the department pursuant to section 251-3, and that is subject to the surcharges imposed by this section shall not be subject to the surcharges imposed by section 251-2; provided that any organization registered with the department pursuant to section 251-3 shall be subject to at least one surcharge imposed by this chapter.