The ornamental design for a frontportion of an automobile, as shown and described.
FIG. 1 is a front perspective view of a front portion of an automobile showing my new design;
FIG. 2 is a rear perspective view thereof;
FIG. 3 is a right-side view thereof;
FIG. 4 is a left-side view thereof;
FIG. 5 is a top view thereof;
FIG. 6 is a front view thereof; and,
FIG. 7 is a rear view thereof.
The claimed design is indicated by the relatively dark portions in FIGS. 1-7, while the relatively light portions thereof are environmental and form no part of the claimed design.