Presented by RENNtech – Introduced in 2017, the M256 -engine marked the return of the inline 6 cylinder to the Mercedes-Benz family. The 3.0 -liter engine with EQ Boost, a 48V mild-hybrid system that adds power and torque on request, is silky smooth and inherently well balanced.

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Developed in two versions, the M256 can be found in the current 450 and AMG 53 line up. The 450 -version has a Dyno measured power rating of 392 hp, and the AMG 53 -version 436 hp, great numbers, numbers that RENNtech was quick to improve upon.

For the 450 -version, found in CLS, GLE, and GLS -models, RENNtech?s ECU upgrade develops an additional 60 hp and 76 lb-ft of torque, bringing the total power output up to 452 hp and 475 lb-ft. The figure is easy to remember; the 450 delivers 450 HP, and 14 hp more than the standard AMG 53 version of the engine.
For the AMG 53 version, found in the CLS, and
E-class, the RENNtech ECU upgrade uncorks an additional 49 HP and 46 lb-ft
of torque, boosting the total power figure up to 485 HP and 456 lb-ft.
Track tested, the RENNtech tuned CLS AMG 53 is powerful and quick,
running down the ¼ mile in 12.1 seconds with a trap speed of 114 mph!

The M256 engine is a sharp, technologically advanced engine with a pleasing tone of nostalgic inline 6-cylinder sound. And with the RENNtech ECU upgrade, both the 450 and AMG 53 move into a new and exhilarating territory. After all, what RENNtech does best is to i...