2021 Mercedes-Benz S-Class — Full Specifications
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The 2021 Mercedes-Benz S-Class is a saloon/sedan offered with 2 engines (3L 6-cyl, 4L 8-cyl turbo). Its most fuel-efficient configuration returns around 24 mpg (UK) / 20 mpg (US EPA) combined, with 20–29 mpg (UK) across all configurations. A hybrid version is also listed by EPA (3L 6-cyl), returning around 29 mpg (UK) combined. Owners often keep a Mercedes-Benz S-Class workshop manual to hand for servicing and repairs.
Compared with the 2020 Mercedes-Benz S-Class: Fuel economy slips from 26 to 24 mpg (UK) combined on the most efficient configuration. EPA lists new engine options for 2021: 3L 6-cyl. No longer listed: 3L 6-cyl turbo, 6L 12-cyl turbo. EPA passenger volume changes from 112 to 88 cu ft.
Full Specifications
| Engine (most efficient) | 4L 8-cyl turbo |
|---|---|
| Engine options | 3L 6-cyl · 4L 8-cyl turbo |
| Transmission (most efficient) | Automatic 9-spd |
| Fuel Type | Premium Gasoline |
| Powertrain | Conventional |
| Drive | Rear-Wheel Drive |
| Body Style | Saloon/Sedan |
| Passenger Volume (EPA) | 88 cu ft (2,492 L) |
| Luggage Volume (EPA) | 7 cu ft (198 L) |
| Fuel Economy (UK) | 24 combined / 19 urban / 31 extra-urban mpg |
| Fuel Economy (US EPA) | 20 combined / 16 city / 26 highway mpg |
| CO₂ Emissions | 282 g/km |
| EPA Greenhouse Gas Score | 4 / 10 (10 = lowest emissions) |
| EPA Est. Annual Fuel Cost | $4,100 (15,000 mi/yr, US prices) |
Engine & Transmission Options
EPA lists 4 configurations for the 2021 Mercedes-Benz S-Class across 2 engines (3L 6-cyl, 4L 8-cyl turbo). Combined fuel economy ranges from 17 to 24 mpg (US), or 20 to 29 mpg (UK), depending on engine, transmission and drive. The headline figures at the top of this page describe the most fuel-efficient configuration.
| Engine | Transmission | Drive | MPG (UK) | MPG (US) | CO₂ g/km | Fuel cost / yr |
|---|---|---|---|---|---|---|
| 3L 6-cyl (Hybrid) | Automatic 9-spd | 4-Wheel Drive | 29 | 24 (20/29) | 231 | $3,400 |
| 4L 8-cyl turbo | Automatic 9-spd | 4-Wheel Drive | 20 | 17 (14/24) | 317 | $4,850 |
| 4L 8-cyl turbo (Hybrid) | Automatic 9-spd | 4-Wheel Drive | 23 | 19 (16/24) | 291 | $4,350 |
| 4L 8-cyl turbo | Automatic 9-spd | Rear-Wheel Drive | 24 | 20 (16/26) | 282 | $4,100 |
MPG (US) shows combined, with city/highway in brackets. Highlighted row = the configuration used for the headline figures. Source: US EPA fueleconomy.gov.
EPA measures interior passenger volume at 88 cubic feet (about 2,492 litres) and luggage volume at 7 cubic feet (about 198 litres). These are US EPA interior-volume figures; they are measured differently from the boot capacity numbers UK manufacturers quote.
Owner Essentials for the 2021 Mercedes-Benz S-Class
Running Costs: 2021 Mercedes-Benz S-Class
Covering around 8,000 miles a year in a 2021 Mercedes-Benz S-Class at 24 mpg combined, expect roughly 1,515 litres of fuel annually — multiply by your local price per litre for a cost estimate. For US owners, the EPA estimates about $4,100 a year in fuel for the most efficient configuration (15,000 miles, national average prices). Work out exact fuel costs with the fuel cost calculator on 247Calculators.
Convert between MPG and L/100km with the unit converters on 247QuickTools. Not sure what tyre size fits? 247TyreCheck explains tyre sizing.
Only need this car occasionally? See our buy vs rent comparison.
2021 Mercedes-Benz S-Class Safety Ratings (NHTSA)
No NHTSA crash-test rating is on record for this model year. The NHTSA rates only a subset of vehicles each year; you can browse every rated vehicle on our NHTSA Safety Ratings hub.
Recalls & Owner Complaints (NHTSA)
NHTSA lists no safety recall campaigns for the 2021 Mercedes-Benz S-Class as of 6 October 2026. Recalls can be issued years after a model is sold, so it is still worth checking your own VIN.
Owners have filed 34 complaints with NHTSA about the 2021 Mercedes-Benz S-Class. The most-reported areas are Electrical system (10), Wheels (6), Forward collision avoidance (5). Complaints include 2 reported crashes, 3 reported injuries, 1 reported death. That is well above the median of 22 complaints across the 15 Mercedes-Benz S-Class model years in our data.
Used-buyer checklist for the 2021 Mercedes-Benz S-Class
Based on where NHTSA recalls and owner complaints cluster for this model year, these are the areas worth checking before you buy:
- Electrical system (10 owner complaints) — Test every switch, window, light and warning lamp on a test drive, and ask about battery or alternator replacements.
- Wheels (6 owner complaints) — Look for bent or cracked wheels and ask about any wheel recalls.
- Driver-assist sensors (5 owner complaints) — Check that driver-assist warning lights are off and sensors are clean and undamaged.
- Engine cooling (5 owner complaints) — Check coolant level, look for leaks and make sure the temperature stays steady in traffic.
Source: US NHTSA recall and consumer-complaint databases, retrieved 6 October 2026. Complaints are unverified owner reports, not confirmed defects. Check any vehicle by VIN at nhtsa.gov/recalls, and see our guide to checking a used car for recalls.
How It Compares
Mercedes-Benz models in our database average about 26 mpg (UK) combined on their most efficient configuration; the 2021 Mercedes-Benz S-Class's 24 mpg is 2 mpg below that make average. Its 282 g/km CO₂ figure is 14 g/km higher than the 268 g/km Mercedes-Benz average.
Of the 17 Mercedes-Benz S-Class model years we cover, the 2021 ranks 4th for combined fuel economy on its best configuration (24 mpg UK combined, against a high of 26 mpg). See every Mercedes-Benz S-Class year side by side.
Last updated: · Data: US EPA (fueleconomy.gov) and NHTSA safety ratings 18 July 2026; NHTSA recalls and complaints 6 October 2026; Wikidata & curated EU catalogue 18 July 2026; European generation and engine data from Wikipedia 7 October 2026
Vehicle data sourced from manufacturer specifications. Always verify with your vehicle handbook or a qualified mechanic. This is a reference tool, not professional advice.
Recommended Accessories for the 2021 Mercedes-Benz S-Class
Frequently Asked Questions
What engine does the 2021 Mercedes-Benz S-Class have?
EPA lists 2 engines for the 2021 Mercedes-Benz S-Class: 3L 6-cyl, 4L 8-cyl turbo. The most fuel-efficient configuration pairs the 4L 8-cyl turbo with a automatic 9-spd.
What is the fuel economy of the 2021 Mercedes-Benz S-Class?
The most efficient configuration returns around 24 mpg (UK) combined, or 20 mpg on the US EPA cycle. Across all configurations the UK combined figure runs from 20 to 29 mpg. The hybrid version returns around 29 mpg (UK) combined.
How much does the 2021 Mercedes-Benz S-Class cost to fuel per year?
The US EPA estimates about $4,100 a year in fuel for the most efficient configuration, based on 15,000 miles of mixed driving and national average fuel prices. Your own cost will depend on mileage and local prices.
Does the 2021 Mercedes-Benz S-Class have any recalls?
NHTSA lists no safety recall campaigns for the 2021 Mercedes-Benz S-Class as of 6 October 2026. Recalls can be issued years after a model is sold, so it is still worth checking your own VIN.
What are the most common problems reported for the 2021 Mercedes-Benz S-Class?
Among the 34 owner complaints filed with NHTSA, the most-reported areas are Electrical system (10 complaints), Wheels (6 complaints), Forward collision avoidance (5 complaints). Complaints are unverified owner reports, not confirmed defects, and raw counts rise with how many cars were sold.
How much interior and luggage space does the 2021 Mercedes-Benz S-Class have?
EPA measures interior passenger volume at 88 cubic feet (about 2,492 litres) and luggage volume at 7 cubic feet (about 198 litres). These are US EPA interior-volume figures, which are measured differently from the UK boot-capacity numbers manufacturers quote.