Trunk comparison: BMW iX1 vs Seat Ibiza

Key Differences
The BMW iX1 offers significantly more length in cargo space: with the seats folded down, the trunk is 8.3 in (15%) longer, and with the front seats upright, even 8.7 in (32%) longer than in the Seat Ibiza. The width of the trunk opening is also noticeably better in the iX1: 8.3 in (24%) wider than in the Ibiza.
In contrast, the Seat Ibiza has a higher opening and a significantly deeper trunk floor: the opening is 3.9 in (14%) higher, and the depth from the loading edge to the trunk floor is 6.7 in (850%) greater than in the iX1.
Implications for Usability
The longer loading surfaces in the iX1 make it more practical for long items (e.g., slats, skis, furniture parts) and overall more flexible with variable seat usage: even with the front seats upright, larger loads can be accommodated.
The wider opening of the iX1 makes loading wide or bulky objects easier and reduces the risk of edges or trim getting caught when loading.
The higher opening area and significantly greater depth in the Ibiza offer other advantages: taller items can be loaded more easily because the opening starts higher, and items can be "sunken" into the deeper recess so they protrude less in the trunk and shift less.
This is practical for stackable groceries or smaller, bulky items that need to lie stably.
In practice, this means: those who frequently transport long or wide loads have the better solution with the BMW iX1; those who often carry bulky but rather taller or deeper loads or everyday groceries benefit from the Seat Ibiza.
Smaller differences like the 1.2 in higher loading edge of the iX1 or the 0.4 in narrower bottleneck in the Ibiza are hardly relevant in everyday use.