FIG. 1 is an isometric view of a convertible car cover showing our new design where the broken lines showing a car is for illustrative purposes only and forms no part of the claimed design;

FIG. 2 is a top view thereof;

FIG. 3 is a side view thereof;

FIG. 4 is a back view thereof;

FIG. 5 is a front view thereof; and,

FIG. 6 is a bottom view thereof.