Trunk comparison: BMW 5 Series Touring vs BMW X3

Key Differences (>10%)
The biggest differences concern the usable cargo length with the first row of seats upright and the height of the trunk opening.
The BMW 5 Series Touring offers a cargo area that is 5.5 in (≈15%) longer with the first row upright than the BMW X3. Conversely, the BMW X3 has a trunk opening that is 3.5 in (≈13%) higher than the 5 Series Touring.
Impact on Usability
The longer cargo length of the 5 Series Touring with the rear seats upright makes it more practical when frequently transporting longer items without folding down the seats – for example, long boxes, pipes, skis, or furniture parts.
Users who regularly carry long, narrow loads (craftsmen, athletes with equipment) benefit from less maneuvering and less frequent seat folding.
The higher trunk opening of the X3 makes it easier to load and unload tall or bulky items. Items with considerable height or volume (large boxes, strollers, bulky household appliances) can be loaded more easily through the larger opening; loading and positioning cargo is also less restricted.
Other measurements (equal trunk depth, X3’s loading edge height only ~6% higher, width differences 3–6%) are comparatively small and have little decisive impact in most everyday situations.
In short: 5 Series Touring = clear advantage for longer cargo without folded seats; X3 = advantage when loading tall or bulky items. For mixed use, it depends on the priority (length vs. height).