Will VITTSJÖ Shelf unit, black-brown/glass, 39 3/8x68 7/8 " fit in an Alfa Romeo 159 2010?

The 159 gives you plenty of height at the opening and less width than you would like. The mouth measures 36⅝″ wide by 50¾″ tall, so tall boxes go in easily, and the floor matches it at 36⅝″ across its narrowest point. Length runs 40⅛″ with the seats up and 69⅝″ folded, a gain of 29½″. Wide, rigid cartons are the ones that fight you here. The sill is 30⅜″ off the ground with a 9⅞″ drop to the floor, so lift over the lip and lower, rather than sliding.

VITTSJÖ ships as one long, flat carton, 79¼″ × 15¼″ × 3½″ and 60 lb 12 oz. The length is the awkward part: a rigid flat-pack just under 80 inches that will not bend around a tight boot mouth, and there is glass inside, so the box does not forgive a hard knock. A car that takes it easily is an estate, an SUV, or a hatchback with the rear seats folded flat. In anything smaller, load it diagonally from a folded seat back toward the boot, longest edge leading, and rest it on a blanket. Keep it printed side up so the glass shelves stay flat, and slide it in rather than drop it.