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Transmission
Christian von Koenigsegg invented the Koenigsegg Direct-Drive System (KDD), and it was developed for the Regera by the Koenigsegg Advanced Engineering Team.[29] The KDD system effectively eliminates the need for a transmission and allows for pure EV (electric vehicle) mode. The Regera doesn't have a traditional multi-gear transmission but instead features a single-speed fixed-gear transmission, often called a direct-drive, with a 2.73:1 reduction ratio, meaning the crankshaft mounted on the ICE will rotate 2.73 times for every 1 time that the output shaft of the direct-drive mechanism will rotate.[30]

At speeds below 30 mph, the wheel shaft electric motors mostly propel the car through the use of a hydraulic coupling that lets the ICE and the crankshaft mounted electric motor slip. In reverse, only the wheel shaft electric motors propel the car.[10][31] Above 30 mph, the RPM of the crankshaft mounted electric motor and internal combustion engine are proportional to wheel speed through locking of the hydraulic coupling.[10] However, Christian von Koenigsegg described and demonstrated how the Regera features a steering-wheel-mounted paddle that simulates a traditional downshift by initiating slip of the hydraulic coupling connecting the crankshaft to the output shaft. This results in higher RPM of the ICE and the crankshaft mounted electric motor and therefore higher power at lower speeds than what would have been possible if the coupling would have been locked at all times.[32] Koenigsegg reported that the omission of a gearbox and addition of electric motors and battery only added 88 kg (194 lb) compared to what the Regera would have weighed with the same combustion engine but a 7-speed dual-clutch transmission (DCT) and no electric motors or batteries.[11][33]

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Koenigsegg