BMWs high tech S58

Our first glimpse of the twin-turbocharged straight-six set to power the next M3 and M4


BMWS INLINE SIX-CYLINDER engines have earned the Bavarian marque a place as one of the greats when it comes to powerplants. The M3 has, for three of its five generations, been the flagship of BMWs inline six-cylinder performance engines, and it seems the next engine is going to continue that lineage in a rather spectacular fashion. A 375kW-plus, 7200rpm fashion.

But the engine set to power the G20 M3 (and its eventual M4 sibling) once its revealed has already been dropped into another model. Its still one of Ms creations, but its not a hardcore sports car as would traditionally debut a new high-powered M motor. Its an SUV. Specifically, its two variations of the same SUV platform, BMWs X3 M and X4 M.

The S58, a development of the already-prolific B58 twin-turbo 3.0-litre engine, brings with it an impressive set of numbers that should translate into a similarly impressive M3. Take the power figures offered up by the X3/X4 M Competition as an example, 375kW is already well north of the 331kW the F90 M3 Competition offers, and 600Nm from the new engine matches the highest-spec F90 M3: the CS.

That previous engine, the S55, has been around for about half a decade now, and is based on the B55 which is double that age. Perhaps one of the most impressive aspects of the new engine is the massive advance in output figures, while becoming more efficient and meeting those emissions targets. BMW has managed to include in the engines peripherals four catalytic converters and two petrol particulate filters.

All four versions of the M SUV, standard and Competition for each body style, produce only marginally more carbon dioxide than the much smaller and less powerful BMW M2 Competition. Thats not taking into account the new, harsher tests under the WLTP, which the M2s tests preceded.

Whats more, its not unreasonable to expect more to come from the S58. Its unlikely BMW would bring a new engine out of the gates without leaving some headroom for facelifts and powered-up models later in its life.

Advances in the production process for the engine have also allowed BMWs engineers to create what it claims is a stronger engine block, with a closed-deck crankcase design and a 3D-printed cylinder head core allowing higher internal engine pressures without adding more weight to the engine.

Some of that extra pressure is coming in via the new TwinPower Turbo setup which BMW claims now loses less pressure than it previously did thanks to a new intake.

Fuel injection pressure also gets a boost, from 200 bar to 350 bar, or over 5000psi. The higher pressure more finely atomises the fuel resulting in lower emissions, BMW says, especially under full load and at high engine speeds. If driving faster is greener, were happy to oblige.