Any municipality which has more than one taxing district may by a majority vote of its legislative body set a uniform city-wide mill rate for taxation of motor vehicles, except that if the charter of such municipality provides that any mill rate for property tax purposes shall be set by the board of finance of such municipality, such uniform city-wide mill rate may be set by a majority vote of such board of finance. No uniform city-wide mill rate may exceed the amount set forth in § 12-71e.