Reserve 1/2 cup of the frosting. Tint remaining frosting with food color. Place whole loaf on tray. Frost top with 1/3 cup tinted frosting. Top with cut layer, positioning for desired car. Trim corners for more rounded look if desired. Attach cookies for wheels, using small amount of frosting. Draw outline of windows with sharp knife. Frost windows and hubcaps with reserved white frosting. Frost sides and top of car with remaining tinted frosting, building up around wheels for fenders.