When Mercedes announced its new turbocharged 2.0-liter engine, it did so with the proclamation it was the most powerful four-cylinder engine ever. We had to dig to confirm Mercedes’ assertion, and all we could find was the Mitsubishi Lancer Evolution FX-440 MR that made 440 horsepower from its 2.0-liter four-cylinder engine – 24 more than the Mercedes. However, the company only made 40 examples for the UK. But according to Mercedes-AMG’s head of engine development Ralph Illenberger, who spoke with Carsales, an even more powerful version is possible.

Illenberger said the engine has yet to reach its peak performance, adding that there’s more to come with room for improvement. However, he said it was a challenge to bring the current 2.0-liter mill to a street-legal car. He concluded by saying, “We’ll see what the future will bring.”

Gallery: Mercedes-AMG M139 Four-Cylinder Engine

Right now, Mercedes offers the M 139 engine in two performance flavors – standard and S. The higher powered S makes 416 hp (310 kilowatts) and 369 pound-feet (500 Newton-meters) of torque. The standard M 139 mill produces 382 hp (285 kW) and 354 lb-ft (480 Nm) of torque. Adding a third tune doesn’t seem too outside the realm of possibility. Both versions of the engine use a twin-scroll turbocharger with the S engine producing up to 30.5 psi (2.1 bar) of boost while the standard engine makes up to 27.6 psi (1.9 bar).

The engine will find its way into the Mercedes-AMG A45. However, U.S. consumers will get their first taste of the mill in the CLA 45 sedan. Spy photos hint the engine could end up in the GLB-Class crossover, too. If Mercedes wrings more power out of its 2.0-liter engine, it may keep the little engine at the top of the most potential four-pot mills. Then again, no reign lasts forever.

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