Mercedes-Benz plans to discontinue the current SL43’s four-cylinder M139 engine when the SL model undergoes its mid-cycle refresh in 2027, as the engine cannot meet the upcoming Euro 7 emissions standards. It will be replaced by the M256 Evo 3.0-liter inline-six mild-hybrid powertrain, and the new model will be named the AMG SL53. This engine delivers a maximum output of 449 horsepower, supplemented by a 23-horsepower integrated starter-generator. Unlike the rear-wheel-drive SL43, the SL53 will come standard with all-wheel drive. Additionally, the current 4.0-liter twin-turbocharged V8 engines used in the SL55 and SL63 will also be revised, switching from the existing cross-plane crankshaft to a flat-plane design to enhance performance and comply with new emissions regulations. Following the update, the SL55’s output will increase to 537 horsepower, and the SL63’s will rise to 650 horsepower—gains of 68 hp and 73 hp, respectively, over the current models. The report did not specify details regarding potential updates to the SL63 S E Performance plug-in hybrid variant. This model currently combines the V8 engine with an electric motor for a combined output of 805 horsepower; if equipped with the new V8, its total output could exceed 880 horsepower.