Trunk comparison: BMW X4 vs Mercedes Benz GLB

Main Differences

When comparing, it is particularly noticeable that the Mercedes-Benz GLB offers a significantly different vertical and loading geometry: the height of the trunk opening is +7.1 in (26%) larger on the GLB, and the depth between the loading edge and trunk floor is +1.6 in (50%) greater than on the BMW X4. Smaller differences concern the length (with folded seats, the GLB is +2 in / 3% longer; with the front seats upright, the BMW X4 is +2.8 in / 7% longer), the width at the narrowest point (+2 in / 5% in favor of the GLB), and the width of the trunk opening (+1.2 in / 3% in favor of the GLB).

The loading edge of the BMW X4 is +2.8 in (10%) higher above the road than that of the GLB.

Impact on Usability

The significantly higher trunk opening of the GLB makes it easier to load tall items (e.g., suitcases, strollers, boxes) and reduces the risk of bumping against the opening; large items can be positioned more easily in an upright position.

The greater depth between the loading edge and trunk floor in the GLB means more vertical space in the trunk and thus more room for stacking or bulky, tall cargo inside.

For the BMW X4, the higher loading edge has a rather negative effect: heavy cargo must be lifted higher, making loading and unloading more strenuous.

On the other hand, the X4 offers slightly more length with the front seats upright, providing easier space for longer, flat-loadable items (e.g., skis, longer boards), which is advantageous for users needing a longer usable area. Width differences are minor and hardly decisive in practice.

Conclusion: For frequent loading of tall or bulky items, the GLB is more practical due to the larger opening and deeper loading geometry.

For longer, flat-lying cargo, the X4 scores slightly with its greater length with the seats upright; however, the higher loading edge of the X4 makes handling heavy objects less comfortable.