Trunk comparison: Kia Sportage vs Opel Grandland

Key Differences
With the seats folded down, the length measurements of both models are the same. With the front row upright, the Kia Sportage is minimally longer (+0.4 in / 1%) — negligible in practical terms.
The biggest differences concern the build height and the depth of the trunk: the trunk opening of the Opel Grandland is 3.1 in or 11% higher than that of the Kia, and the distance from the loading edge to the trunk floor in the Opel is 6.3 in or 1500% greater than in the Kia.
All other dimensions (loading edge height above the road +2.4 in / 8%, narrowest width +1.2 in / 3%, opening width +1.2 in / 3%) are below the 10% mark and are secondary.
Impact on Usability
The significantly higher trunk opening in the Grandland makes it easier to load tall or bulky items: boxes, plants, or pieces of furniture need to be tilted less and fit more easily through the opening.
The substantially greater depth from the loading edge to the trunk floor in the Grandland increases the usable cargo volume especially vertically and allows goods to be stored deeper (more "storage depth").
This is advantageous for longer or bulky items that should not protrude over the backrest or when you want to hide cargo below the loading edge.
In contrast, the Kia has a flatter trunk floor: reaching items far back is easier because you don't have to bend as deeply, and the slightly wider narrowest trunk width (+1.2 in) makes storing very wide but flat items slightly easier.
Additionally, the loading edge in the Kia sits a bit lower (Opel +2.4 in), which makes lifting heavy items over the threshold somewhat easier — a practical advantage in everyday use when regularly lifting heavy loads.
Conclusion: For frequent transport of tall or very deep/long items, the Opel Grandland is the more practical choice due to the higher opening and significantly greater trunk depth.
For frequent loading and unloading of heavy or flat items where a low loading edge and easier access are important, the Kia Sportage has slight advantages.