Mercedes-AMG could replace the SL 43’s 4-Cylinder with a straight-six
11/04/2026
The move would mark more than a simple engine swap.
For a brand built on thunderous engines and emotional performance, the idea of an AMG sports car powered by a four-cylinder engine was always going to be controversial. And now it seems Mercedes-AMG may be quietly reversing course.
The current Mercedes-AMG SL 43, powered by a highly sophisticated 2.0-liter turbocharged four-cylinder could soon disappear from the lineup. In its place, AMG is reportedly preparing a new SL 53 equipped with a 3.0-liter straight-six mild-hybrid engine.
The four-cylinder experiment may be ending
When Mercedes-AMG introduced the SL 43, the car arrived with the brand’s advanced M139 four-cylinder engine, one of the most technically impressive production engines ever built. With 416 horsepower from just two liters, the engine pushed the boundaries of what a four-cylinder could achieve.
But despite its impressive engineering credentials, the reception among traditional AMG customers was… mixed. Many buyers struggled with the idea of a flagship AMG roadster powered by the same basic engine architecture found in smaller models such as the Mercedes-AMG A45.
Now regulatory pressure may be giving AMG the perfect excuse to rethink the formula. Reports suggest the M139 engine may struggle to comply with Euro 7 emissions and noise regulations, accelerating the decision to replace it entirely.
A straight-six comeback
The rumored replacement would bring a more traditional AMG layout back into the SL lineup. The new SL 53 is expected to use the M256 Evo 3.0-liter inline-six mild-hybrid powertrain, delivering around 449 horsepower, a noticeable increase over the current SL 43.
Interestingly, the upgrade would also reportedly bring all-wheel drive, replacing the rear-wheel-drive layout of the SL 43. That change would push the entry-level SL much closer to the performance territory currently occupied by the Mercedes-AMG SL 55, which produces 469 horsepower.
The V8 models are evolving too
The changes wouldn’t stop with the entry-level model. The SL 55 and Mercedes-AMG SL 63 are also expected to receive updates as part of the upcoming facelift. Both models will reportedly continue using AMG’s 4.0-liter twin-turbo V8, but with a new flat-plane crankshaft design, a layout typically associated with high-revving supercars.
Power outputs could increase significantly:
SL 55: around 537 hp
SL 63: up to 650 hp
That would create a wider performance spread across the SL range while helping AMG meet tightening emissions targets. At the top of the lineup, the extreme SL 63 S E Performance plug-in hybrid (currently producing 812 horsepower) could also receive further updates.
AutoNext Take
The four-cylinder experiment was technically brilliant, but emotionally it never quite fit the image of an AMG roadster. A straight-six, however, feels much closer to the brand’s heritage.
It offers smoother delivery, richer sound and a character that aligns better with the expectations of buyers in this segment. In other words, this might be one of those rare moments where regulations and enthusiast expectations actually point in the same direction.
