The Mercedes — Benz M 273.968 is a 5,461 cc, V8 naturally aspirated petrol engine produced between 2006 and 2011. It features dual overhead camshafts (DOHC), variable valve timing (VVT) on both intake and exhaust camshafts, and a dry — sump lubrication system in certain high — performance variants. Delivering 270–300 kW (367–408 PS) and 530–540 Nm of torque, it provides strong mid — range power delivery ideal for grand touring applications.
Fitted to models such as the W221…
Production years 2006–2009 meet Euro 4 standards; 2010–2011 models meet Euro 5 depending on market .
The Mercedes-Benz M 273.968 is a 5,461 cc V8 naturally aspirated engine engineered for luxury and performance vehicles (2006–2011). It combines dual overhead camshafts with variable valve timing on both intake and exhaust to deliver smooth power delivery and responsive mid-range torque. Designed to meet Euro 4 and select-market Euro 5 standards, it balances high performance with acceptable fuel economy for its class.
| Parameter | Value | Source |
|---|---|---|
Displacement | 5,461 cc | |
Fuel type | Petrol | |
Configuration | 90° V8, DOHC, 32-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 96.9 mm × 92.4 mm | |
Power output | 270–300 kW (367–408 PS) | |
Torque | 530–540 Nm @ 2,700–4,000 rpm | |
Fuel system | Sequential multi-point fuel injection (ME-SFI) | |
Emissions standard | Euro 4 (2006–2009); Euro 5 (2010–2011, market-dependent) | |
Compression ratio | 10.5:1 | |
Cooling system | Water-cooled | |
Turbocharger | Not applicable | |
Timing system | Double-row roller chain (integrated cam adjusters) | |
Oil type | Refer to vehicle handbook / manufacturer specification | |
Dry weight | 210 kg |
The Mercedes-Benz M 273.968 was used across Mercedes-Benz's W221/W212 platforms with longitudinal mounting and shared architecture with AMG variants in high-performance applications. This engine received platform-specific adaptations-reinforced engine mounts in the W221 and revised intake manifolds in the R230-and from 2009 the facelifted W212 models adopted updated camshaft adjusters, creating interchange limits. All adaptations are documented in OEM technical bulletins.
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Analysis derived from manufacturer technical service bulletins and industry workshop records. Repair procedures should follow manufacturer guidelines.
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The M 273.968 delivers smooth power and strong performance, but early models (2006–2008) had reliability concerns, especially camshaft adjuster failures. Later revisions (post-2009) improved adjuster durability, so well-maintained examples can be robust. Regular servicing and using high-quality oil (5W-40 MB 229.5) greatly aid longevity.
The biggest issues are camshaft adjuster wear (leading to rattling or timing faults), crankcase ventilation (CCV) clogging, and intake manifold runner binding. Other complaints include ignition coil failures and occasional fuel injector deposits. These are well-documented in Mercedes-Benz service bulletins.
This 5.5L V8 was used in several luxury models during the 2006–2011 period. It powered the S-Class (W221 S500), E-Class (W212 E500), SL-Class (R230 SL500), and CL-Class (C216 CL500). It replaced the M113 V8 and was succeeded by the M276 turbocharged V6 in most applications.
Yes, but with limitations. As a naturally aspirated engine, power gains from ECU remapping are modest (+15–25 kW). More significant increases require forced induction (supercharger/turbo) or displacement upgrades. Tuning should preserve factory valve timing and fuel delivery to avoid reliability issues.
Moderate for a V8. In an S500 (W221), typical consumption is ~14.0 L/100km (city) and ~8.5 L/100km (highway), or about 20 mpg UK combined. Real-world figures depend on driving style, but expect 18–24 mpg (UK) on mixed roads. Premium fuel (98 RON) is recommended for optimal performance.
Yes. The M273 series is an interference engine. If the timing chain fails or jumps, pistons can collide with open valves, causing catastrophic engine damage. Chain maintenance and timely adjuster replacement are critical to prevent this.
Mercedes specifies a 5W-40 synthetic oil meeting MB 229.5 specification. Always use a high-quality oil designed for high-performance petrol engines and change it every 15,000 km or annually to ensure proper adjuster lubrication and minimize sludge buildup.
Comprehensive technical documentation and regulatory references
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GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
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