Mercedes-AMG just gave its V8 a flat-plane crankshaft to keep it alive
The most important change is one you cannot see, but you will hear it
Mercedes-AMG has revised its GLE 63 S 4MATIC+ and GLS 63 4MATIC+, but the styling and suspension updates are not the headline. The headline is under the bonnet: the AMG V8 now has a flat-plane crankshaft, a fundamental change designed to keep this engine legal and alive for years to come. The new M177 EVO still produces 612 hp, but it is a meaningfully different engine from the one it replaces.
Why a flat-plane crankshaft is a big deal for AMG
AMG V8s have traditionally used a cross-plane crankshaft, which gives them their characteristic deep, burbling rumble. A flat-plane crank is the layout you find in a Ferrari V8: it reduces rotating mass, lets the engine rev more freely and sharpens throttle response. The trade-off is a higher, harder-edged sound. AMG says the change improves the engine's ability to rev and ensures particularly precise response. In other words, this engine will feel and sound different from every fast AMG V8 that came before it.
The reason behind it is regulatory survival. Board member Michael Schiebe was explicit: "With the new M177 EVO generation, we have fundamentally revised the power unit and secured its presence in our portfolio for the long term." The engine now meets the latest emissions standards worldwide, with a particulate filter fitted as standard, while continuing to deliver what AMG calls a pronounced appetite for revs.
The numbers
The 4.0-litre biturbo V8 produces 612 hp and 850 Nm of torque, the latter available from 2,500 to 4,500 rpm. A 48-volt mild-hybrid system with an integrated starter generator (ISG) 2.0 adds another 23 hp and 205 Nm, smoothing power delivery, enabling energy recuperation and supporting low-rev torque. The GLE 63 S 4MATIC+ hits 100 km/h in 3.9 seconds, the larger GLS 63 4MATIC+ in 4.2 seconds, and both top out at 280 km/h. Power goes through the AMG SPEEDSHIFT TCT 9G transmission and the Performance 4MATIC+ all-wheel-drive system. As before, each engine is hand-built in Affalterbach under the "One man, one engine" philosophy.
New face, sharper chassis
Both SUVs get a redesigned front with the latest AMG radiator grille, enlarged air intakes and a new LED light signature, plus twin tailpipes and a reworked diffuser at the rear. Underneath, AMG RIDE CONTROL+ air suspension pairs with AMG ACTIVE RIDE CONTROL active roll stabilisation, which analyses the road up to 1,000 times per second to keep body roll in check. A Trail driving programme raises ride height by 55 mm for light off-road work. Inside, the new MB.OS operating system brings AMG-specific displays for torque distribution, G-forces and engine data, alongside the usual extensive MANUFAKTUR personalisation options.
AutoNext Take
Switching to a flat-plane crank is the most significant thing AMG has done to its V8 in years, and it tells you exactly how hard the brand is fighting to keep eight cylinders alive. After the painful four-cylinder C 63 experiment, AMG has clearly heard the message that its customers want the V8, and reengineering the M177 from the crankshaft up to survive future regulations is a serious commitment rather than a cosmetic refresh. The open question is the sound. A flat-plane AMG V8 will rev harder and bark sharper, but it will not rumble the way the cross-plane engines did. Some loyalists will mourn that. Most will simply be relieved the V8 is still here at all.
