Trunk comparison: Audi A4 Avant vs VW Golf Wagon (Mk5)

Key Differences
The trunk length of both models is the same with the first row of seats upright; however, when all seats are folded down, the Audi A4 Avant offers a trunk floor that is +5.1 in (8%) longer than the VW Golf 5. The trunk opening of the Audi A4 Avant is significantly higher by +4.3 in (15%) compared to the VW Golf 5. Depth (loading edge to trunk floor) and most width measurements differ only minimally: the loading edge of the Golf is +0.4 in (2%) higher, the narrowest trunk width of the Golf is +0.4 in (1%) larger, and the width of the trunk opening of the A4 Avant is +0.4 in (1%) larger.
Impact on Usability
The only significant deviation over 10% is the higher trunk opening of the Audi: this noticeably facilitates loading tall or bulky items, reduces the need to tilt cargo, and improves handling comfort with bulky objects (e.g., furniture, boxes, strollers).
The 5.1 in longer cargo floor with folded seats in the A4 Avant provides additional space for longer items, but with an 8% advantage, it is rather moderate and mainly affects regular transport of long goods.
The slightly higher loading edge of the Golf (+0.4 in) and the ±0.4 in width differences are negligible in practice and hardly affect everyday usability.