Mercedes E-Class S214 Engines — The Complete UK Guide
Every engine fitted to the S214 estate — from the OM654 2.0-litre four-cylinder diesels to the M254 2.0-litre petrols, the M256 3.0-litre straight-sixes, and the M256-based AMG E53 Hybrid. All S214 engines are four- or six-cylinder units with 48V mild-hybrid or plug-in hybrid assistance — Mercedes has electrified the entire E-Class range. Backed by real UK S214 enquiries in 2025 [MB-VERIFIED].
Explore S214 Engines
Mercedes E-Class S214 Engine Codes — The Complete Database
Every engine fitted to the S214 estate specifically — all are mild hybrid or plug-in hybrid units, marking the first time the E-Class estate has been offered exclusively with electrified powertrains.
Overview
Mercedes E-Class S214 — Overview
The S214 is the estate body style of the sixth-generation E-Class, launched in May 2023 as the successor to the S213 estate.
Based on the MRA2 platform, it features a longer wheelbase and increased interior space. For the first time, every S214 E-Class is equipped with an electrified powertrain — 48V mild hybrid or plug-in hybrid — with no purely combustion-engined options available. The engine range spans the OM654 2.0-litre four-cylinder diesel, the M254 2.0-litre four-cylinder petrol, the M256 3.0-litre straight-six petrol, and the OM656 3.0-litre straight-six diesel. Plug-in hybrid options (E 300e, E 350e, E 400e, E 300de, AMG E 53 Hybrid) use a 25.4 kWh battery offering up to 71 miles of all-electric range.
Key Facts
Platform
Mercedes MRA2
Predecessor
S213
Successor
— (current generation)
Sibling body styles in this generation
W214 Saloon, X214 All-Terrain
Market Intelligence
The S214 E-Class estate is the current-generation model; enquiry volumes are growing as early 2023–2024 cars exit manufacturer warranty and enter the used market.
Best & Worst Engines
Best Diesel Overall
OM656.XXX (E 450d, 3.0-litre straight-six diesel)
“The 3.0-litre OM656 is one of the most powerful diesel engines Mercedes has ever produced — 367 hp and 750 Nm of torque, with 48V mild-hybrid assistance. It's a refined, smooth straight-six that delivers effortless performance while maintaining genuine economy. Introduced in 2017, the OM656 has proven itself as a robust, durable engine.”
Who it's for: buyers who want effortless diesel torque and six-cylinder refinement without the complexity of a V8.
Best Petrol Overall
M256.830 (E 450, 3.0-litre straight-six petrol)
“The 3.0-litre M256 straight-six is a masterpiece of modern engineering — 381 hp, 500 Nm of torque, and the smoothest six-cylinder petrol Mercedes has made since the M104. Introduced in 2017, it replaced the M276 V6 and has proven itself as a refined, reliable powerplant. The 48V mild-hybrid system and integrated starter-generator deliver seamless start-stop and electric boost.”
Who it's for: buyers who want the pinnacle of petrol refinement in an E-Class estate.
Highest Risk
M254-based PHEVs (E 300e, E 350e, E 400e)
“The M254 four-cylinder petrol is a newer engine, and the complex 25.4 kWh plug-in hybrid system adds significant complexity. The combination of combustion engine, electric motor, and hybrid battery creates more potential failure points than a conventional powertrain. While early signs are positive, long-term reliability data is limited.”
Who it's for: buyers who prioritise low company-car tax and electric commuting over long-term simplicity.
Most Expensive Failure
M256-based AMG E 53 Hybrid
“The AMG E 53 Hybrid's powertrain is the most complex ever fitted to an E-Class estate — a 3.0-litre M256M straight-six with an electric auxiliary compressor, a 161 hp electric motor, and a 25.4 kWh battery, producing 604 hp combined. When something goes wrong, it goes wrong expensively. The electric turbocharger, the hybrid system, and the sheer labour intensity of working on this engine mean replacement costs will be eye-watering.”
Who it's for: buyers with deep pockets who want the most powerful E-Class estate ever.
Best Value
OM654.820 (E 220d, 2.0-litre four-cylinder diesel)
“The E 220d is the volume diesel for good reason — 197 hp, 440 Nm of torque, genuine 50+ mpg economy, and the same robust OM654 as the more powerful variants. It's cheaper to buy, cheaper to run, and cheaper to replace than the six-cylinder diesels. The sweet spot in the S214 range for most UK buyers.”
Who it's for: buyers who want the best combination of economy, performance, and reliability in the S214 range.
Most Overlooked
OM654.820 (E 300de plug-in hybrid diesel)
“The E 300de is the most overlooked engine in the S214 range — a 2.0-litre OM654 diesel combined with a 129 hp electric motor and 25.4 kWh battery, delivering 313 hp combined and up to 71 miles of electric range. It's the ultimate company car choice — low BIK tax with diesel economy for long journeys.”
Who it's for: company car drivers who need the lowest possible tax bills with genuine long-distance capability.
Mercedes E-Class S214 — Ownership Economics
The S214 rule
A £3,500–£5,500 OM654 recon against a £30,000 S214 sits at 12–18% of the car's value — comfortably safe. Even the M254 at £3,000–£6,000 against a £28,000 E 200 is 11–21% — well within our 70% Mercedes threshold. The S214 is a current-generation car with strong retained values; engine replacement is financially viable across the range. The only exception is the AMG E 53 Hybrid — but if you can afford a £70,000+ car, you can afford the maintenance. For PHEV variants, battery health is the bigger long-term concern.
Common Problems
S214 Engine Replacement Costs — By Engine and Condition
No Generation variance from the Model Page's baseline figures — S214 estate shares its MRA2-derived engine bay with the W214 saloon and X214 All-Terrain, so costs are inherited directly per the Authority Model, with no divergence note required. M256 AMG costs reflect AMG-specific parts, the electric auxiliary compressor, hybrid system components, and specialist labour requirements.
Core Variants
Core Variants
Scope note: All variants listed are S214 estate only. W214 Saloon and X214 All-Terrain share most of these engines but are covered on their own Generation Pages, as fitment and labour access vary slightly by body style. The S214 estate's 25.4 kWh battery is shared across PHEV variants.
Market Intelligence
Most Requested E90 Engines (2025)
- 1.1. OM654.820 (E 220d) — volume diesel [PATTERN DATA]
- 2.2. M254.920 (E 300) — volume petrol [PATTERN DATA]
- 3.3. M256.830 (E 450) — six-cylinder enthusiast choice [PATTERN DATA]
Most Requested E90 Variants
- 1.1. E 220d
- 2.2. E 300
- 3.3. E 450 [PATTERN DATA]
Average E90 Replacement Cost
£3,000–£6,500 reconditioned, supply only [MB-QUOTE]
Most Common E90 Failures
- 1.1. 48V mild-hybrid system issues
- 2.2. PHEV battery degradation
- 3.3. Software/electrical glitches [PATTERN DATA]
Mercedes E 220d S214 (OM654)
5
enquiries
Mercedes E 300 S214 (M254)
3
enquiries
Mercedes E 450 S214 (M256)
2
enquiries
FAQ
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