The ornamental design for a frontportion of an automobile, as shown and described.
FIG. 1 is a right front perspective view of a front portion of an automobile of our new design;
FIG. 2 is a right side elevation thereof, the left side being a mirror image thereof;
FIG. 3 is a right rear perspective view thereof;
FIG. 4 is a front elevation view thereof;
FIG. 5 is a rear elevation view thereof; and,
FIG. 6 is a top plan view thereof.
The portions of the automobile in light shading are environment, and form no part of the claimed design. The bottom view of the front portion of the automobile forms no part of the claimed design.