Mercedes-AMG A45 S By Posaidon Is The Hottest Of Hot Hatchbacks

German tuning firm Posaidon has unleashed it's versions of the Mercedes-AMG A45 S. As expected, it's based on the current A45 S with the M139 turbocharged four-cylinder motor – the most powerful four-cylinder engine in production. But since we're talking about Posaidon, 415 horses from a blown mill is not enough.

In fact, Posaidon is offering two upgrades for the Mercedes-AMG A45 S. The milder version benefits from an upgraded turbo software to free up more horses under the hood. According to Posaidon, this model is good for 465 horsepower and a 0 to 60 mph time of 3.6 seconds. The stock version achieves the same feat in 3.9-seconds, so adding more horses is a good idea, indeed.

However, things get crazier is you choose the spiciest version of Posaidon's AMG 45 S. Affectionately referred to as the RS 525 depicted here, it has skunkworks version of the M139 engine producing 525 horsepower. The power upgrade was courtesy of a larger turbocharger and a remapped ECU.

The result of all this madness is astonishing. The RS 525 rushes from 0 to 60 mph in 3.4 seconds and has a top speed of 201 mph. Meaning, this bright yellow hatchback is as fast as a supercar, high-strung compact, or tuned muscle car.

Posaidon's not yet done, though. The tuning company is currently working on a Plus model of the RS 525. Nothing specific yet, but Posaidon did say the Plus model is currently undergoing development.

Back home, the most powerful version of Mercedes-AMG's M139 engine is found in the CLA 45, GLA 45, and GLB 45. European-spec models are offered in S versions with 416 horsepower, while U.S.-bound non-S models have 382 horsepower and 354 pound-feet of torque.

The good news? Posaidon is offering all the aforementioned performance upgrades to any member of the AMG 45 lineup. Fancy a 200 mile-per-hour GLB or CLA? You know who to call.