In-depth reviews

Mercedes S-Class saloon - MPG, running costs & CO2

Engines offer respectable efficiency but the plug-in hybrid model could be the smart choice

Carbuyer Rating

4.5 out of 5

Owners Rating

4.0 out of 5

Read owner reviews
MPG, running costs & CO2 Rating

4.5 out of 5


  • Incredibly refined
  • Class-leading technology
  • 62-mile electric range for PHEV


  • High running costs
  • Only one petrol engine
  • Expensive to buy

The Mercedes S-Class range is made up of 3.0-litre and 2.9-litre six-cylinder mild-hybrid petrol and diesel engines. Larger V8 engines are expected in 2021, followed by a plug-in hybrid model that can run in EV mode for over 60 miles.  

Mercedes S-Class MPG & CO2

Kicking off proceedings, the diesel S 350 d is available with rear- or four-wheel drive, and it can manage up to 42.8mpg, while emitting 173g/km of CO2. Step up to the S 400 d; only available in combination with 4MATIC four-wheel drive and long wheelbase, and fuel consumption drops to 38.7mpg and 192g/km of CO2. This means the diesel S-Class sits in the top Benefit-in-Kind band for business operators.

The petrol S 500 4MATIC gets EQ Boost mild-hybrid hardware, giving it up to 34.9mg (32.5 for the long wheelbase) with CO2 emissions of 184g/km. Every new S-Class is fitted with a nine-speed automatic gearbox. Car tax will cost £150 a year but because the S-Class exceeds the £40,000 mark, owners will also need to pay a £325 surcharge in years two to six.

An S 580e plug-in hybrid will arrive later with a 3.0-litre petrol engine and 28kWh battery giving it up to 62 miles on a charge. That's around twice the electric range currently offered by the Audi A8 or BMW 7 Series.

Insurance groups

Insurance groups have yet to be confirmed but cover isn't likely to be cheap. Even entry-level versions of its predecessor sat in group 44 out of 50, while top trims are in the highest group.


Like the rest of the Mercedes range, the S-Class comes with a three-year/unlimited-mileage warranty, which is roughly the same as the cover Audi A8 and BMW 7 Series buyers get. The S-Class is also covered by roadside assistance across Europe.


If owners are wondering when the car's next service is due, they'll now be able to ask the car's MBUX voice assistant. Mercedes ServiceCare will be offered, spreading the costs of servicing across monthly payments and guaranteeing the cost of parts and labour for up to four services.

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