Mercedes-Benz GLC X254 — Reliability

X254 2023–present 1 engine

Reliability Summary

Engine M177 AMG — 65/100 CAUTION
Known Issues 3

Engine in this model

CAUTION 65

M177 AMG

4.0L TT V8

Handcrafted AMG V8. Massive power. AMG-level care needed. Expensive when wrong.

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Known Issues Across All Engines

Issue Engine Severity Onset
Head bolt failure — early C63 (W205) M177 AMG critical —
Oil degradation — M-car intervals critical M177 AMG high —
Intake carbon buildup (direct injection) M177 AMG moderate 60,000 km – 120,000 km