Trunk comparison: VW ID.4 vs VW Tiguan

Key Differences
The most noticeable difference lies in the depth of the trunk (loading edge to trunk floor): the VW ID.4 is 3.5 in deeper, which according to the data corresponds to a difference of +900%. This is the only size specification that clearly exceeds the 10% mark and is therefore particularly relevant for usability.
Other, smaller deviations: With the seats folded down, the Tiguan is 1.2 in (≈2%) longer, with the first row of seats upright the ID.4 has about 2.4 in (≈7%) more trunk depth.
The height of the trunk opening of the ID.4 is about 2.4 in (≈8%) above that of the Tiguan. The loading edge height and the narrowest width of the trunk are the same in both models; the width of the trunk opening is about 0.8 in (≈2%) larger in the Tiguan.
Impact on Usability
The significantly greater trunk depth of the ID.4 practically means more usable interior space below the loading edge: taller items can be placed deeper and thus more stably, boxes or bags can be stacked better, and delicate cargo sits further inside instead of just at the opening.
This makes the ID.4 advantageous when frequently transporting tall or bulky items.
The slightly higher trunk opening of the ID.4 makes it marginally easier to load tall objects compared to the Tiguan, while the same loading edge height in both models requires comparable effort when lifting.
The same narrow interior width means that wide items fit equally well (or limited) in both vehicles; the Tiguan's 0.8 in larger opening width offers only a marginal advantage here.
The 1.2 in longer loading floor in the Tiguan with folded seats and the 2.4 in longer usable depth of the ID.4 with the first row upright are small differences that can be relevant for occasional special loading tasks (e.g., particularly long items), but in everyday use are usually less decisive than the significantly greater depth of the ID.4.
Conclusion
If you frequently transport tall or bulky cargo, the ID.4 is more comfortable and practical due to its significantly larger trunk depth. For users who mainly transport very long, flat items and regularly fold down the seats, the Tiguan offers a minimally longer loading area — however, the advantage is small.