the 2027 Mercedes S-Class introduces updated powertrains that focus on stronger performance, improved efficiency, and tougher emissions controls. This guide explains what changed under the hood, how the 48-volt mild hybrid systems work, how each engine performs in real use, and which powertrain fits different buyers. It also includes clear data, expert analysis, pros and cons, common pitfalls, and a short future outlook for Mercedes’ combustion and hybrid strategy.
Why these engine updates matter
The S-Class is Mercedes’ flagship sedan. Buyers expect refinement, effortless acceleration, and modern emissions compliance without compromising the luxury experience. The 2027 engine updates deliver three main benefits:
- More usable power for confident cruising and overtaking.
- Improved efficiency and emissions via mild hybridization and targeted hardware changes.
- Preserved refinement so the car remains quiet and smooth at low load.
Key terminology and components
- M177 EVO — Updated 4.0-liter twin-turbo V8 used in S 580 variants.
- M256 EVO — Updated 3.0-liter turbocharged inline-6 used across S 450 / S 500 lines.
- OM656 EVO — Updated 3.0-liter inline-6 diesel tuned for lower emissions.
- 48-volt mild hybrid — Electrical system that provides torque fill, better stop-start and recuperation; includes integrated starter generator.
- Plug-in hybrid (S 580e) — Combines combustion engine and electric motor for higher combined output and short all-electric range.
- Electrically heated catalytic converter — Device that warms the catalyst quickly at cold start to reduce emissions.
M177 EVO V8: What’s new and who it’s for
The M177 EVO is a 4.0-liter twin-turbo V8 tuned to deliver strong, immediate power with refined manners expected in a flagship sedan. Key points:
- Output: Around 530 hp and 553 lb-ft of torque.
- Hybrid assist: A 48V mild hybrid system smooths stop-start, provides torque fill at low rpm, and helps recover energy during braking.
- Character: Focused on internal refinement—revised combustion strategy and mechanical updates to improve throttle response without adding NVH (noise, vibration, harshness).
Who should choose it: buyers who want effortless acceleration and a muscular engine note but still expect quietness at low load. It is ideal for long-distance luxury cruising with the occasional need for brisk overtakes and high-speed runs.
Real-world performance and efficiency
The V8’s 530 hp places it firmly in the performance luxury category. The 48V system helps reduce fuel consumption in stop-and-go traffic and improves low-speed drivability, but a V8 will still consume more fuel than the inline-6 or PHEV during spirited driving. Expect strong mid-range acceleration and relaxed cruising at highway speeds.
M256 EVO inline-6: balance of power and economy
The M256 EVO is an evolved 3.0-liter inline-six that aims to be the backbone of the S-Class lineup. Its main features:
- Output: Approximately 442 hp and 443 lb-ft of torque, with an overboost function raising torque transiently to around 472 lb-ft.
- Integrated starter generator: Works with the 48V system to deliver immediate torque and smoother restarts.
- Driving character: Smooth, responsive, and powerful enough for a large luxury sedan while offering better baseline fuel economy than the V8.
Who should choose it: buyers who want near-V8 performance in daily driving but prefer better fuel economy and lower running costs. The transient overboost makes merging and overtaking effortless.
Practical considerations
- The inline-6 provides a balance of refinement and economy, especially on long cruises.
- Maintenance costs are typically lower than for the V8, due to fewer cylinders and potentially less stress on components.
OM656 EVO diesel: updated for emissions and range
Where diesel remains relevant, the OM656 EVO continues as Mercedes’ updated 3.0-liter inline-six diesel. Updates focus on emissions reduction and efficiency without sacrificing the diesel torque advantage:
- Lower cold-start emissions thanks to an electrically heated catalytic converter that brings exhaust aftertreatment up to working temperature faster.
- Mild hybrid assistance helps with stop-start smoothness and recuperation, improving real-world fuel economy.
- Long range remains a diesel strength, suitable for buyers with lots of motorway driving.
Who should choose it: drivers covering high mileages, those in regions where diesel still offers tax or fuel advantages, and buyers who value maximum range and torque for towing or sustained high-speed travel.
S 580e plug-in hybrid: performance plus electric flexibility
The plug-in hybrid variant combines combustion power with an electric drive unit. Notable points:
- Combined output: Around 576 hp when both systems work together.
- Electric driving: Short all-electric range suitable for urban commutes and low-emission zones; reduces fuel use for typical daily driving patterns.
- Use case: Buyers who want near-supercar combined performance on demand yet can often do daily trips on electric power, lowering overall fuel costs.
Charging and usability
PHEV owners should consider typical daily range, available home or workplace charging, and whether short all-electric trips match their routines. A PHEV is most beneficial when charged regularly; otherwise, it behaves more like a heavier, more complex hybrid with limited fuel-saving benefits.
How the 48-volt mild hybrid and integrated starter generator work
The 48V mild hybrid is not a full electric drive. It provides key benefits:
- Torque fill during turbo lag or gear shifts to make acceleration feel seamless.
- Stop-start improvement with quicker and smoother restarts for comfort and efficiency.
- Regenerative braking to recover energy that normally would be lost.
- Transient overboost to temporarily increase torque for overtaking or acceleration.
These systems reduce fuel use in urban and mixed driving and preserve the cinematic, quiet S-Class character at low power demands.
Expert analysis: engineering trade-offs and market strategy
Mercedes’ approach is evolutionary rather than revolutionary. Key observations:
- Refinement over headline numbers — improvements prioritize smoothness and usable torque curves rather than chasing peak horsepower alone.
- Transitional electrification — 48V systems and PHEVs are practical steps that lower emissions and improve drivability while keeping combustion engines relevant.
- Diesel retention — updating diesel with electrically heated catalysts shows Mercedes understands regional market needs where diesel still offers benefits.
- Complexity and cost — added systems increase manufacturing and maintenance complexity; buyers will trade some simplicity for efficiency and emissions improvements.
What this means for buyers
Expect excellent real-world smoothness and near-instant throttle response across the range. Buyers who want top performance will favor the V8 or PHEV. Those prioritising daily economy and lower emissions should choose the inline-6 or PHEV and ensure charging is part of their routine. Diesel remains the choice for long-range efficiency where infrastructure and regulations still support it.
Pros and cons of the 2027 S-Class powertrains
Pros
- Improved power and torque across the range while keeping smoothness.
- Better emissions control with electrically heated catalysts and mild hybridization.
- Flexible lineup with V8, inline-6, diesel, and PHEV options for different buyer needs.
- Enhanced drivability due to 48V torque fill and integrated starter generator.
Cons
- Higher complexity increases maintenance demands and potentially repair costs.
- V8 fuel consumption remains high compared to six-cylinder and PHEV alternatives.
- PHEV weight and system complexity can affect handling and long-term battery maintenance.
- Diesel availability is region-dependent and may face regulatory changes in some markets.
Common buyer questions and practical answers
Which engine is best for daily commuting?
The M256 EVO inline-6 or the S 580e plug-in hybrid are the best picks. The inline-6 gives refined performance with better fuel economy than the V8, while the PHEV can cover short commutes on electric power and significantly lower fuel use if charged regularly.
Is the V8 necessary for S-Class refinement?
No. The inline-6 is very refined and will satisfy many buyers. The V8 is about stronger acceleration and a distinctive engine character rather than basic refinement alone.
How much real fuel saving does the 48V system provide?
48V mild hybrid systems typically yield modest fuel savings in urban cycles and better responsiveness. Expect better stop-start behavior, lower idling fuel use, and small percent improvements in mixed driving. Exact savings depend on driving patterns.
Are diesel S-Class models still worth it?
For high-mileage drivers and markets with favorable diesel pricing or tax regimes, yes. The OM656 EVO targets lower cold-start emissions and delivers strong range and torque.
Maintenance and ownership considerations
- Hybrid components such as the 48V battery and integrated starter generator will have their own service schedules—confirm warranty coverage and replacement costs.
- Diesel aftertreatment systems, including heated catalysts and particulate filters, require occasional active regeneration and may be sensitive to short-trip urban use.
- Complexity of PHEV means additional systems like high-voltage batteries and charge controllers—ensure charging habits are consistent to get full benefit.
- Insurance and taxation may differ between engine types; check local incentives for PHEVs or penalties for higher emissions engines.
Pitfalls and misconceptions
- Misconception: 48V systems make a car electric. Clarification: They assist and improve efficiency but do not provide full electric driving like a PHEV or EV.
- Pitfall: Buying a PHEV without regular charging reduces its advantage and increases complexity without delivering expected fuel savings.
- Misconception: Diesel is always cleaner. Clarification: Modern diesels can be very efficient and low in CO2, but they require complex aftertreatment to manage NOx and particulates especially on cold starts.
- Pitfall: Ignoring regional fuel and emissions rules—diesel and high-displacement engines may face restrictions in some cities or countries.
Future prediction: where Mercedes is heading
Short term: expect continued refinement of combustion engines with hybrid assistance. Mercedes will likely keep improving aftertreatment and electrification features to meet stricter global emissions standards while retaining combustion options where demand remains.
Medium term: plug-in hybrids will become more capable with longer electric range and faster charging. Energy-dense battery packs and software integration will make PHEVs more compelling for luxury buyers.
Long term: full electrification is inevitable for most markets. The combustion engine will persist in specialized roles and markets with different infrastructure and regulatory timelines. Mercedes is likely to transition flagship models progressively to fully electric variants while preserving combustion-derived choices in selected regions during the transition.
Frequently asked questions (FAQs)
- Q: How much horsepower does the M177 EVO make?
A: Around 530 horsepower and approximately 553 lb-ft of torque in S 580 applications.
- Q: What is the benefit of an electrically heated catalytic converter?
A: It reduces emissions during cold starts by bringing the catalyst to operating temperature faster, which cuts harmful emissions before the normal exhaust heat can do so.
- Q: Will the PHEV S 580e replace the V8?
A: Not completely. The PHEV offers high combined output with electric flexibility, but the V8 remains for buyers desiring its specific sound and performance character.
- Q: Are maintenance costs higher for these newer engines?
A: Complexity increases maintenance scope. Hybrid components, advanced aftertreatment, and higher-pressure systems can lead to higher servicing costs than older, simpler engines. Warranty and dealer service plans can mitigate these costs.
Conclusion
The 2027 S-Class engine updates refine what buyers expect from a flagship luxury sedan: stronger and more usable performance, better emissions control, and improved efficiency thanks to 48V mild hybrid systems and targeted hardware changes. The M177 EVO V8 delivers authoritative performance, the M256 EVO inline-6 balances power and economy, and the OM656 EVO diesel remains a practical choice where long range and diesel infrastructure matter. The S 580e PHEV blends electric flexibility with high combined output for buyers who can charge regularly.
Choosing between these powertrains comes down to priorities: raw character and acceleration (V8), daily efficiency with strong performance (inline-6), long-range and torque for highways (diesel), or the lowest urban fuel use and emissions when charged (PHEV). Understanding hybrid behavior, regional regulations, and maintenance implications will ensure the S-Class experience aligns with ownership expectations.