Trunk comparison: Audi Q5 vs Seat Tarraco

Key Differences
The SEAT Tarraco offers a significantly longer usable length in the trunk: with the seats folded down, it is +8.3 in (13%) longer than the Audi Q5, and with the rear seats upright, the advantage is +6.7 in (18%).
In contrast, the Audi Q5 has a significantly greater interior/bottom depth: the depth (loading edge to trunk floor) is +0.8 in (33%) higher in the Q5 than in the Tarraco.
Smaller differences, but less relevant, include: the trunk opening height is +1.6 in (5%) larger in the Tarraco, the Tarraco's loading edge is +0.4 in higher above the ground, the narrowest interior width is +0.8 in larger in the Q5, and the opening width is +0.8 in larger in the Tarraco.
Impact on Usability
The longer loading surface of the Tarraco (both with folded seats and with the rear bench upright) makes it more practical for long items such as slats, furniture panels, skis, or long boxes; even for everyday transports, the Tarraco offers more usable cargo space in the longitudinal direction.
The greater longitudinal volume makes it easier to store long or awkward parts without folding down the seats.
The greater depth in the Q5 (loading edge to trunk floor) means more usable depth/volume vertically in the loading area – this is advantageous when items need to be stacked or something taller needs to stand in the trunk.
Additionally, a deeper cargo area can influence the center of gravity when loaded and make it easier to store heavy items closer to the vehicle's center.
The other differences (opening height, loading edge height, a few centimeters in width) are small and have hardly noticeable effects in everyday use: a slightly higher opening in the Tarraco makes sliding in very tall items easier, while the minimally larger interior width in the Q5 only helps with particularly wide parts.
Conclusion: Those who frequently transport long items or need more length reserve are better served by the SEAT Tarraco. Those who benefit from a deeper loading area (better stacking, somewhat more volume in depth) will find advantages in the Audi Q5.