Trunk comparison: Audi A6 Avant vs Opel Grandland

Key Differences
The Audi A6 Avant offers significantly more cargo length: with the seats folded down, the trunk is 10.6 in (16%) longer, and with the first row upright, it is even 11 in (31%) longer than in the Opel Grandland.
The Opel Grandland, on the other hand, has a higher trunk opening and different height dimensions of the loading area: the opening height is 3.1 in (11%) higher, the depth from the loading edge to the trunk floor is 5.5 in (700%) greater, and the loading edge itself is 5.5 in (22%) higher above the road than in the Audi.
The width differences are minor (at the narrowest point +1% and opening width +4%) and practically negligible.
Impact on Usability
For long items and lots of luggage behind the rear seats, the Audi A6 Avant is clearly advantageous: the longer cargo areas allow transporting bulky, longer goods (e.g., laminate, long pipes, skis, or furniture parts) without or with only partial folding of the seats.
The Opel Grandland scores with vertical accommodation of tall or bulky items: the higher opening height and greater depth between the loading edge and trunk floor create more vertical space and make it easier to load tall objects.
However, the loading edge in the Grandland is significantly higher (+5.5 in), which makes lifting heavy loads into the trunk more strenuous; for heavy or frequently loaded items, the lower loading edge of the Audi is more practical.
Overall, this means: Audi = better for long or flat loads and easier loading/unloading with a lower loading edge; Opel = better for tall or bulky volume loads but requires more effort when lifting due to the higher loading edge.