Will BRIMNES Cabinet with doors, white, 30 3/4x37 3/8 " fit in a Citroen C5 Aircross 2021?

The C5 Aircross gives you a wide, square loading mouth: 41″ across and 30¾″ tall, with a floor that is actually wider than the opening at 41¾″ between the arches. Seats up you get 38¼″ of length; folding them stretches that to 67¾″, a gain of 29½″. The catch is the sill, which sits 29⅛″ off the ground, though the floor drops only 1⅝″ behind it, so boxes slide in level rather than falling in. Wide flat packs do well here; very long ones run out of floor before they run out of mouth. Lift heavy boxes to sill height first, rest them, then push.

The BRIMNES cabinet arrives as one flat box, 39″ × 16¾″ × 6″, weighing 72 lb 7 oz. The size is friendly; the weight is not. At 39″ long it clears the folded load floor of almost any car, and plenty of boots take it with the seats still up, so this is one of the easier IKEA packages to move by car. What catches you is lifting 72 lb of dense flat-pack over a sill on your own. Slide it on its long edge rather than carrying it flat, bring a second pair of hands for the kerb and the stairs, and protect the corners; chipboard shows every knock at the edges.