Trunk comparison: BMW i4 vs Mercedes Benz GLB

Key Differences

In terms of trunk dimensions, the GLB shows clear strengths especially in three areas: The height of the trunk opening is 31% higher in the GLB, the trunk depth (loading edge to trunk floor) is 20% greater, and the narrowest width of the trunk is 19% wider than in the BMW i4. Additionally, the width of the trunk opening in the GLB is 13% larger.

Smaller differences include: the BMW i4 offers a trunk that is 1.2 in (≈3%) longer with the front seats upright, and with the seats folded down, the GLB is only 0.4 in (≈1%) longer. The loading edge height above the road is 0.8 in (≈3%) higher in the GLB.

Impact on Usability

The significantly larger opening height and width as well as the greater interior width and depth of the GLB make it more practical for bulky and cumbersome cargo: tall items (e.g., boxes, strollers, small furniture) fit more easily through the opening and can be loaded upright, wide goods (e.g., wide suitcases, sports equipment) are more likely to fit without jamming, and the greater depth creates additional usable space behind the loading edge.

In short: the GLB is better suited for everyday use when frequently transporting bulky, tall, or wide items.

The BMW i4 has only minor length advantages with normal loading arrangements and a slightly lower loading edge, which makes lifting heavy items marginally easier.

However, these advantages are small (<10%) and only marginally affect usability: the i4 remains preferable for users who do not regularly transport very tall or particularly wide cargo and who value a lower loading edge and sporty sedan characteristics.

Conclusion

If you regularly load tall, wide, or bulky items, the Mercedes-Benz GLB is the better choice due to its significantly larger opening height, interior width, and depth.

For mostly everyday luggage and occasional transports, the differences are practically less relevant; here the BMW i4 can be sufficient and more convenient due to its somewhat lower loading edge.