Lightweight design in rail vehicles is essential for improving energy efficiency, reducing operational costs, and minimizing greenhouse gas emissions. This paper explores the structural considerations and design principles for the car body of a lightweight, two-axle regional rail vehicle developed under the Horizon Europe Project “FutuRe.” Using a methodical lightweight design approach, including topology optimization, the study minimizes structural mass and identifies optimal design strategies. Results show that longitudinal loads from EN 12663-1 and the placement of heavy equipment like batteries have minimal impact on structural weight.