Trunk comparison: Hyundai Elantra GT Wagon vs Kia Sportage

Key Points
There are two clear differences in usable cargo space: The Hyundai i30 Wagon offers a 5.9 in (≈17%) longer trunk with the first row of seats upright than the Kia Sportage. When the seats are folded down, both models are almost the same length: the i30 Wagon is only 3.5 in (≈5%) longer.
The loading edge of the Sportage, however, is 3.9 in (≈16%) higher above the road than that of the i30 Wagon. Other dimensions differ only slightly: trunk opening height of the Sportage +2.4 in (≈9%), width at the narrowest point +0.8 in (≈2%), opening width +2.8 in (≈7%), depth (loading edge → trunk floor) identical.
Impact on Usability
Because the i30 Wagon is significantly longer with the first row of seats upright, it is better suited for longer items without folding the seats down (e.g., slats, skis, long boxes).
For users who frequently need to transport long but not very tall or wide cargo, the i30 offers a noticeable advantage in everyday configurations.
The higher loading edge of the Sportage makes loading heavy items more strenuous and increases the leverage required when lifting boxes or tires; for regular loading of heavy loads, the i30 is therefore more comfortable.
The higher loading edge can be an advantage for off-road use or vehicles with higher ground clearance, but it is a disadvantage for pure loading comfort.
All other differences (opening height, widths, depth) are minor and hardly affect everyday practicality. A small advantage of the Sportage is slightly more width at narrow points and a somewhat larger opening width; this marginally facilitates loading and unloading bulky but not too long items.