The W177 Mercedes-AMG A 45 S 4Matic+ is the company’s latest and greatest hot hatch that made its debut back in July 2019. Powered by the world’s most powerful turbocharged four-cylinder engine, it packs 421 PS (416 hp) and 500 Nm of torque, which allows for a zero to 100 km/h time of just 3.9 seconds.

Those are some healthy figures, but Brabus thinks it can do better, so say hello to the new B45. No, this isn’t a high-performance take on the B-Class – as funny as such a thing might sound – but Brabus’ attempt at squeezing more power out of the A 45 S’ M139 2.0 litre turbo-four powerplant.

The B45 features the company’s 450 performance upgrade, which includes a new mapping for the engine management system, a special duct for the airbox, along with its proprietary PowerXtra CPC auxiliary control unit and BoostXtra adapter.

With these parts installed, the B45 makes 450 PS (444 hp) and 550 Nm, which represent a gain of 29 PS (28 hp) and 50 Nm. These gains help to reduce the century sprint time from 3.9 seconds to 3.7 seconds, although the top speed remains electronically capped at 270 km/h.

To go along with the added grunt, Brabus also fitted its Monoblock Z 20-inch wheels, which are an inch larger than stock. Featuring a ten-spoke design with polished surfaces to contrast the primarily black finish, the wheels are paired Continental SportContact 6 tyres in a 245/30 profile.

For a more aggressive stance, the B45 also gets sport springs that are height-adjustable, allowing owners to lower the ride height by as much as 30 mm. Unlike other Brabus creations, the bodywork remains unchanged, although the interior can be specified with a variety of items like illuminated scuff plates, Brabus-branded aluminium pedals and velour mats, as well as a range of leather upholsteries.

If you’re interested but have some concerns about getting the 450 performance upgrade, Brabus provides a three-year/100,000-km tuning warranty. It adds that the upgrade has undergone extensive testing on test benches, the Autobahn and race tracks, with type approval from Germany’s strict TÜV (Technical Inspection Association).