Repeals SL 1991-31, which allowed Greensboro to charge a vehicle tax of up to $5 a year for general purposes and up to an additional $5 a year for local public transportation purposes. Amends GS 20-97(b) to allow Greensboro to levy a motor vehicle tax of no more $16 a year and allows up to $5 of the tax to be used for any lawful purpose. Requires the proceeds of the tax from any levy above $5 and up to $16 to be used for local public transportation purposes. The repeal of SL 1991-31 is effective on the date that Greensboro levies a tax under GS 20-97(b). Provides that the act does not affect the rights or liabilities of the state, taxpayer, or another person arising under a statute amended or repealed by the act before the effective date. The act also does not affect the right to any refund or credit of a tax that accrued under the appealed or amended statute before the effective date.