Trunk comparison: Kia Ceed vs Opel Astra Wagon

Key Differences (highlighted: >10%)
Opel Astra Wagon has a 11 in (35%) longer cargo floor length with the first row of seats upright than the Kia Ceed. This means more usable length in everyday use without folding the seats down.
The depth of the trunk (distance from loading edge → trunk floor) is 3.5 in (450%) greater in the Kia Ceed than in the Astra. This means the Kia has a significantly deeper trunk floor relative to the loading edge.
The loading edge of the Kia Ceed is 2.8 in (12%) higher above the road than the Astra, which makes lifting heavy items in more difficult.
Impact on Usability
Due to the greater usable length with the rear seat upright, the Opel Astra is more practical for longer items (e.g., skis, long boxes) that are to be transported without folding down the seats.
The slightly greater width and opening width of the Astra (each by a few cm, under 10%) further supports loading bulky parts.
The Kia Ceed offers a significantly deeper cargo floor, which in practice means more "room downwards" — advantageous for stackable or tall cargo that can be recessed into the trunk.
However, this advantage is offset by the higher loading edge: heavy luggage or boxes must be lifted higher in the Kia, making loading more strenuous than in the Astra.
Conclusion
For regularly transporting long items without folding down the seats, the Opel Astra Wagon is the more practical choice. For more depth-oriented volume (where the cargo is recessed in the trunk), the Kia Ceed offers advantages but suffers from a higher loading edge that complicates loading and unloading.
Which option fits better depends on whether you want to transport longer items (Astra) or rather bulky/deep stackable cargo (Kia).