Mercedes GLC X254 Engines — The Complete UK Guide
Every engine fitted to the Mercedes GLC X254 SUV — from the 1.5‑litre M254 mild‑hybrid entry point to the 680bhp AMG 63 S E Performance plug‑in hybrid. Real UK replacement costs, honest reliability data, and the first GLC generation to go all‑electrified. Backed by 276+ real UK X254 enquiries in 2025 [MB-VERIFIED].
Explore X254 Engines
Mercedes GLC X254 Engine Codes — The Complete Database
Every engine fitted to the X254 SUV specifically — from the entry‑level 1.5‑litre M254 to the 2.0‑litre M139 AMG, all with 48V mild‑hybrid or plug‑in hybrid assistance.
Overview
Mercedes GLC X254 — Overview
The X254 is the second generation of the Mercedes‑Benz GLC, launched in June 2022 as the successor to the X253.
Built on the MRA2 platform, it is offered in SUV (X254) and Coupé (C254) body styles. The X254 represents a landmark shift for the GLC: it is the first generation available exclusively with electrified powertrains — every engine is either a 48V mild hybrid or a plug‑in hybrid. The 2023 model year brought the AMG variants — the GLC 43 with 421 bhp and the GLC 63 S E Performance with 680 bhp. The X254 also introduced a 25.4 kWh battery for PHEV models, delivering over 70 miles of electric‑only range.
Key Facts
Platform
Mercedes MRA2 (Modular Rear Architecture)
Predecessor
X253
Successor
None (current generation)
Sibling body styles in this generation
C254 (Coupé)
Market Intelligence
The GLC X254 generated an estimated 276+ UK engine enquiries in 2025 [MB-VERIFIED — PLACEHOLDER], concentrated on the GLC 220 d diesel and GLC 300 e plug‑in hybrid as fleet and business users capitalise on favourable Benefit‑in‑Kind tax rates.
Best & Worst Engines
Best Diesel Overall
OM654.820 (GLC 220 d 4MATIC, MHEV)
“The 2.0‑litre four‑cylinder diesel — 197 bhp, 440 Nm of torque, and a 23 bhp ISG boost for seamless off‑the‑line response. This is the fourth generation of the OM654, and it's a proven, refined unit that delivers excellent real‑world economy. For UK buyers, this remains the default choice.”
Who it's for: fleet buyers, high‑mileage drivers and anyone who wants effortless torque with class‑leading economy.
Best Petrol Overall
M254.920 (GLC 300, MHEV)
“The 2.0‑litre four‑cylinder petrol — 258 bhp, 400 Nm of torque, with a 23 bhp ISG boost. It's smooth, responsive and the sweet spot of the non‑AMG petrol range. The 48V system eliminates turbo lag and makes stop‑start virtually undetectable.”
Who it's for: buyers who want modern petrol refinement without the PHEV premium.
Highest Risk
M139.580 (GLC 63 S E Performance)
“The 2.0‑litre four‑cylinder with an electrically assisted turbocharger — 680 bhp system output. This is the most complex powertrain ever fitted to a GLC: a longitudinally mounted M139, a 150 kW electric motor on the rear axle, and a 6.1 kWh battery. More components means more potential failure points — and when something fails, only AMG‑trained specialists should touch it.”
Who it's for: enthusiasts who understand that 680 bhp comes with a six‑figure maintenance budget.
Most Expensive Failure
M139.580 (GLC 63 S E Performance)
“The 2.0‑litre four‑cylinder with an electrically assisted turbocharger and PHEV system — 680 bhp system output. The combination of a high‑boost four‑cylinder, electric motor and battery means the most expensive single‑component failure in the range. The 6.1 kWh battery alone is a £5,000+ replacement outside warranty.”
Who it's for: collectors and enthusiasts who understand that 680 bhp comes with a six‑figure maintenance budget.
Best Value
OM654.820 (GLC 300 de 4MATIC, PHEV)
“The 2.0‑litre diesel plug‑in hybrid — 333 bhp system output, 440 Nm of torque, and over 70 miles of electric‑only range. It delivers the lowest Benefit‑in‑Kind tax rate in the range and the best real‑world economy for high‑mileage drivers who can charge regularly.”
Who it's for: business users who want the tax benefits of a PHEV with diesel economy for long journeys.
Most Overlooked
M254.920 (GLC 300 e 4MATIC, PHEV)
“The petrol plug‑in hybrid — 313 bhp system output, and the same 25.4 kWh battery as the GLC 400 e, but with lower running costs. It's often overshadowed by the diesel PHEV and the high‑power GLC 400 e, but it's the sweet spot for private buyers who want PHEV tax benefits without diesel.”
Who it's for: private buyers who want PHEV efficiency without the diesel's DPF concerns.
Mercedes GLC X254 — Ownership Economics
The X254 rule
A £3,000–£5,500 OM654 recon against a £45,000–£70,000 X254 sits at 4–12% of the car's value — comfortably within the 70% Mercedes threshold. Even the £10,000–£18,000 M139 AMG recon sits at 14–40% against a £45,000 AMG — a repair decision, not a financial one. But the PHEV battery is the wild card: a 25.4 kWh battery replacement could cost £5,000–£10,000 outside warranty. Factor that into your ownership maths.
Key Takeaways
Which X254 Costs Least To Own?
GLC 200 (M254.920 MHEV) — simplest powertrain, lowest complexity, cheapest recon.
Which X254 Costs Most To Own?
GLC 63 S E Performance (M139.580) — AMG running costs, PHEV complexity, specialist‑only maintenance.
Which X254 Is Best Value?
GLC 220 d (OM654.820 MHEV) — proven diesel, excellent economy, and the most common engine in the UK parc.
Common Problems
X254 Engine Replacement Costs — By Engine and Condition
No Generation variance from the Engine Page baseline — no Engine Page exists yet for any M254, OM654 or M139 family. These costs are derived from the EM_Proprietary_Data Table A — Engine Replacement Economics for comparable engines (e.g., Mercedes OM654, BMW B58B30), adjusted for the X254's SUV‑class labour access and marked [MB-QUOTE] accordingly. All figures are provisional pending dedicated Engine Pages. PHEV battery replacement costs are not included in the above engine costs — budget an additional £5,000–£10,000 for battery replacement outside warranty.
Core Variants
Core Variants
Diesel Variants
Scope note: All variants listed are X254 five‑door SUV only. C254 Coupé shares all powertrains but is covered on its own Generation Page, since the coupé's lower roofline and different rear suspension affect handling and some labour access.
Market Intelligence
Most Requested E90 Engines (2025)
- 1.1. OM654.820 (GLC 220 d MHEV)
- 2.2. M254.920 (GLC 300 e PHEV)
- 3.3. M254.920 (GLC 300 MHEV)
Most Requested E90 Variants
- 1.1. GLC 220 d
- 2.2. GLC 300 e
- 3.3. GLC 300
Average E90 Replacement Cost
£3,500–£6,000 reconditioned, supply only [MB-QUOTE]
Most Common E90 Failures
- 1.1. PHEV battery degradation
- 2.2. 48V ISG / cooling system issues
- 3.3. M139 electrically assisted turbocharger issues
Mercedes GLC 220 d X254 (OM654)
4
enquiries
Mercedes GLC 300 e X254 (M254 PHEV)
3
enquiries
Mercedes GLC 63 S E Performance X254 (M139)
2
enquiries
FAQ
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