Light transmission along dispersive plasmonic gap with varied gap widths and its subwavelength guidance characteristics are numerically investigated over a wide frequency range. Mode numbers for each guided modes of the dispersive plasmonic gaps are properly assigned in order to be in consistency with the parallel plate waveguide composed of the perfect electric conductor. Overall and salient features of the role of the gap widths on the guided propagation characteristics are clearly understood by investigating several dispersion curves of varied gap widths. Cutoff frequency downshifts of the dispersive plasmonic gap compared with the perfect electric conductor based parallel plate waveguides are also observed. Finally, surface plasmon polariton modes having subwavelength guidance capability are described in more detail, which are directly governed by the plasmonic property of the metals. The results are expected to be utilized in designing various potential subwavelength nanophotonic devices.