This paper presents the design, numerical verification, and experimental assessment of a modular slotted-wall test section for the 2 m × 2 m L2000 low-speed wind tunnel, developed to mitigate wall-induced interference during bluff-body measurements. Nine longitudinal slots enable two selectable open-area ratios (OARs) of 13% and 30%. A 1%-blockage Ahmed body (φ = 12.5°) served as the reference model, with baseline drag and surface-pressure coefficients established by validated simulations. Wind-tunnel tests covering 15–35 m/s and yaw angles −15° ≤ ψ ≤ 15° were conducted both with and without a raised false floor. At low blockage (≤1%) the slotted walls produced only marginal changes in aerodynamic coefficients, while the raised false floor introduced repeatability issues and caused a rear-face pressure rise. These findings show that the present slotted-wall concept offers minimal benefit at low blockage and that the floor–slot interface requires refinement to achieve stable, high-fidelity measurements, particularly at higher blockage levels yet to be tested. The work outlines practical limitations of ventilated walls in subsonic tunnels and identifies critical modifications needed for reliable bluff-body experiments.