Mercedes-AMG is making a strategic U-turn from its controversial four-cylinder hybrid powertrain strategy, acknowledging that the technology “failed to resonate with our traditional customers” despite impressive performance figures. The German performance division is now preparing to phase out the M139 2.0-liter plug-in hybrid system that powers the current C63 and GLC63 models, replacing it with more traditional inline-six and V8 engines enhanced with hybrid technology.
The Four-Cylinder Experiment Falls Short
The M139 2.0-liter four-cylinder plug-in hybrid system, which produces 671 horsepower and 752 lb-ft of torque, represented one of the most technically advanced powertrains in production. However, the impressive numbers couldn’t overcome fundamental customer concerns about the engine’s character and sound quality.
Customer Feedback Drives Change
Mercedes-AMG acknowledged that customers didn’t like the 671-hp plug-in hybrid four-cylinder found in the C63 and GLC63, with criticism focusing on the engine’s “reedy” and “buzzy” sound compared to the symphony of a V8. The four-cylinder system also added significant weight, with the C63’s curb weight reaching nearly 5,000 pounds, negating performance benefits despite the substantial horsepower increase.
Return to Traditional Power
AMG’s future strategy centers on what the company calls a “two pillar” approach, maintaining both electrification and traditional combustion engines. The performance division is developing two primary powertrains to replace the four-cylinder system.
New V8 and Six-Cylinder Strategy
Mercedes-AMG is working on a brand-new V8 engine featuring a flat-plane crankshaft, similar in design to that used by the GT Black Series. Additionally, an updated version of the current 3.0-liter inline-six engine will serve as the foundation for mid-range performance models. Both engines will be electrified with either 48V systems or full hybrid set-ups.
Technical Specifications
The transition timeline remains fluid, with AMG telling Autocar that the four-cylinder will remain in production for the time being before “eventually” being replaced. The 2026 model year is expected to mark the beginning of this transition, with reports suggesting the C63 may adopt the 3.0-liter inline-six hybrid system currently used in the E53 and CLE53 models.
Engine Performance Comparison
| Engine Type | Displacement | Power Output | Torque | Hybrid System |
|---|---|---|---|---|
| Current M139 4-Cyl PHEV | 2.0L | 671 hp | 752 lb-ft | Full Plugin Hybrid |
| Future Inline-Six | 3.0L | 603+ hp | 590+ lb-ft | Mild/Full Hybrid |
| New V8 (Development) | TBD | TBD | TBD | 48V/Full Hybrid |
| Previous V8 (Reference) | 4.0L | 503 hp | 516 lb-ft | Non-Hybrid |
Regulatory Challenges
The decision to abandon the four-cylinder system isn’t purely customer-driven. The M139 powertrain would require expensive reengineering to meet upcoming Euro 7 emissions regulations, making the investment economically challenging.
Euro 7 Impact
The Euro 7 emissions standards, which will apply 30 months after entry into force for cars and vans, introduce stricter requirements for exhaust emissions and new regulations for brake particle emissions. The European Parliament’s Euro 7 agreement establishes comprehensive rules that will affect all vehicle manufacturers operating in the EU market.
According to the official EU Council documentation, the Euro 7 regulation establishes rules for exhaust emissions but also for other types of emissions such as tyre abrasion and brake particle emissions. This comprehensive approach makes compliance significantly more complex and expensive for manufacturers.
AMG’s pivot reflects broader industry challenges in balancing performance, customer preferences, and regulatory compliance. AMG chief Michael Schiebe emphasized that “we need to cater to the demands of customers” while maintaining the brand’s commitment to electrification through hybrid systems.
The transition represents more than just an engine swap – it’s a acknowledgment that advanced technology alone cannot overcome emotional connection and brand identity. As Mercedes-AMG moves forward with its dual-pillar strategy, the focus shifts to delivering electrified performance that maintains the visceral experience customers expect from the AMG badge.
Frequently Asked Questions
Q: When will Mercedes-AMG completely phase out the four-cylinder hybrid?
A: AMG hasn’t provided a specific timeline, only stating it will happen “eventually” with the transition likely beginning around 2026.
Q: Will the new engines be less powerful than the current 671-hp four-cylinder?
A: Initially yes, but AMG plans to develop the new powertrains to deliver competitive performance with better sound and character.
Q: Are all AMG models affected by this change?
A: The change primarily affects the C63 and GLC63 models, though other four-cylinder AMG variants may also transition to alternative powertrains.
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