Parkers overall rating: 4.5 out of 5 4.5

Miles per pound (mpp) Miles per pound (mpp)

Petrol engines 2.6 - 4.7 mpp
Diesel engines 4.7 - 5.3 mpp
Plug-in hybrid petrol engines 47.1 mpp
Low figures relate to the least economical version; high to the most economical. Based on WLTP combined fuel economy for versions of this car made since September 2017 only, and typical current fuel or electricity costs.
Based on "Weighted" mpg; figures depend on the proportion of miles driven in pure electric mode and may vary widely

Fuel economy

Petrol engines 19.8 - 34.9 mpg
Diesel engines 37.7 - 42.8 mpg
Plug-in hybrid petrol engines 353.1 mpg
  • Plug-in hybrid looks worth waiting for
  • Diesels not much more economical than petrol
  • Servicing and maintenance will be expensive

How much does it cost to run?

If you’re going to be clocking up big miles in your Mercedes-Benz S-Class, then the diesel S 350 d is the model to go for to minimise your fuelling costs. But it should be worth noting that the difference in consumption over a petrol model is no longer as significant as it was a few years ago.

MPG and CO2

Fuel economy for the S 350 d ranges between 40.4mpg and 42.8mpg in the real-world WLTP Combined test. The S 400 d is slightly less economical between 37.7-38.7mph, while the S 500 brings up the rear at between 32.8-34.9mpg.

If CO2 emissions are important the S 350 d comes up top with a figure of 173g/km for the skinniest AMG Line model, and that rises to 192g/km for the AMG Line Premium model, while the best S 500 puts out 184g/km. As you can see, the difference between diesel and petrol has really closed up – but it makes no difference for tax purposes.

Business users can expect a 37% BiK tax rate on all S-Class models currently available for the 2021/22 tax year.

Of course, the upcoming S 580 e plug-in hybrid is where it’s going to be if you want to be the most tax-efficient while getting (potentially) the best fuel consumption. The combined WLTP fuel consumption is an intriguing 223.2mpg and CO2 emissions are 56g/km – unlikely, yes, but keep the batteries topped up, do shorter trips and you’ll rarely need fuel.

Ongoing running costs

Road tax (12 months) £510 - £520
Insurance group 50
How much is it to insure?