Trunk comparison: BMW X3 vs Kia Stonic

Key Differences

The BMW X3 offers significantly more cargo length: with the seats folded down, the trunk is 16.1 in (30%) longer and with the first row upright, 10.2 in (38%) longer than the Kia Stonic.

The width of the BMW X3's trunk opening is 5.1 in (13%) larger. On the other hand, the Kia Stonic has a significantly greater depth between the loading edge and the trunk floor: the depth is 7.1 in (1700%) greater than in the BMW X3.

What impact does this have on usability?

More cargo length and a wider opening in the BMW X3 mean: long or flat items (e.g., slats, furniture parts, skis, bulky boxes) are easier to accommodate. The larger opening width improves loading of wide items and makes sliding in bulky cargo easier.

The greater depth difference in the Kia Stonic means its trunk floor lies significantly lower below the loading edge. This offers more vertical space for bulky but not too large items, which can help with bulky, tall loads.

At the same time, the Stonic's loading edge is somewhat higher above the ground (by 2.8 in), making lifting heavy items into the trunk more strenuous.

Additional points: The height of the trunk opening is the same, so both models have the same vertical entry height for tall cargo. The narrowest width inside the cargo area differs only slightly (BMW +2 in) and has less practical impact.

Conclusion: For transporting long or wide items, the BMW X3 is clearly more practical. The Kia Stonic offers more vertical space due to the deeper cargo floor but makes loading heavy items physically more demanding.

Which choice is more sensible depends on typical cargo: long/bulky parts → BMW X3; bulky, not necessarily long items with more floor depth → Kia Stonic.