The Mercedes CLS 350d (3.0D) 286hp (C257 - 2018 - 2020) produces 286bhp and 600Nm in standard form. Our Stage 1 ECU tuning file raises output to 380bhp and 800Nm, a gain of 94bhp and 200Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.