The 2017–2019 Porsche 911 RSR 4.0 (991.2) marked a fundamental departure from Porsche’s traditional rear-engine architecture, adopting a mid-engine configuration by rotating the engine-gearbox unit 180°, placing the engine ahead of the rear axle—akin to the layout of the earlier 911 GT1. Developed entirely anew for the 2017 season, the RSR introduced a redesigned chassis, body structure, aerodynamic package, and drivetrain, all tailored for FIA GTE compliance. This new layout allowed for better weight distribution and enabled a significantly larger and more efficient rear diffuser, paired with a top-mounted rear wing to enhance aerodynamic synergy. Powered by a naturally aspirated 4.0L flat-six engine from the GT3 R and GT3 Cup programs, it delivered around 375 kW (510 PS), depending on air restrictor size, avoiding turbocharging due to weight and cooling disadvantages. The 6-speed sequential gearbox, mounted at the rear, featured a magnesium casing. Additional enhancements included front double-wishbone suspension, a rigidly mounted driver seat positioned closer to the car’s center, and a radar-assisted collision avoidance system with cockpit display. Fuel storage moved to the front trunk area, retaining balance variability across stints. Competing under Manthey Racing, the 991.2 RSR achieved class victories at the 2018 24 Hours of Le Mans and secured the 2018–19 FIA World Endurance Championship GTE Pro title.