  In earlier papers in this series we determined the intrinsic stellar disc
kinematics of fifteen intermediate to late type edge-on spiral galaxies using a
dynamical modeling technique. From the photometry we find that intrinsically
more flattened discs tend to have a lower face-on central surface brightness
and a larger dynamica mass-to-light ratio. This observation suggests that at a
constant maximum rotational velocity lower surface brightness discs have
smaller vertical stellar velocity dispersions.Although the individual
uncertainties are large, we find from the dynamical modeling that at least
twelve discs are submaximal. The average disc contributes 53$\pm$4 percent to
the observed rotation at 2.2 disc scalelengths, with a 1$\sigma$ scatter of 15
percent. This percentage becomes somewhat lower when effects of finite disc
flattening and gravity by the dark halo and the gas are taken into account.
Since boxy and peanut-shaped bulges are probably associated with bars, the
result suggests that at 2.2$h_{\rm R}$ the submaximal nature of discs is
independent of barredness. The possibility remains that very high surface
brightness discs are maximal.We confirm that the radial stellar disc velocity
dispersion is related to the galaxy maximum rotational velocity. The scatter in
this $\sigma-v_{\rm max}$ relation appears to correlate with the disc
flattening, face-on central surface brightness and dynamical mass-to-light
ratio. Low surface brightness discs tend to be more flattened and have smaller
stellar velocity dispersions. The findings are consistent with the observed
correlation between disc flattening and dynamical mass-to-light ratio.
