The ornamental design for a vehicle mounted bannerdevice, as shown and described.
FIG. 1 is a top perspective view of a vehicle mounted banner device according to the present design, with a base mount and a banner element being shown in broken or dashed line format and forming no part of the claimed design of FIGS. 1-7;
FIG. 2 is a leading side view of the vehicle mounted banner device shown in FIG. 1;
FIG. 3 is a trailing side view of the vehicle mounted banner device shown in FIG. 1;
FIG. 4 is a top view of the vehicle mounted banner device shown in FIG. 1;
FIG. 5 is a bottom view of the vehicle mounted banner device shown in FIG. 1;
FIG. 6 is a left side view of the vehicle mounted banner device shown in FIG. 1; and,
FIG. 7 is a right side view of the vehicle mounted banner device shown in FIG. 1.
The broken lines represent features that form no part of the claimed design.