In a C-Class you can choose from two diesel and two petrol engines, each of them turbocharged four-cylinders – and all offering satisfying thrust for normal driving. A fifth option is a petrol-electric hybrid powertrain, supplied with the C350 e, which you can charge from a household power outlet.
Of the four conventional engines, the two diesels are the most fuel efficient and there is little between them for fuel use – even though one makes more power than the other. Both consume about 4.7 litres/100km on the official test (city and country combined).
The less powerful of the diesels arrived in August 2017, when Mercedes replaced the less costly of its C-Class diesels, the C200 d, with the C220 d. The C200 d had a 1.6-litre engine and went about as hard as popular small-car diesels such as the Hyundai i30. In contrast, the C220 d has a 2.1-litre engine, and 25 per cent more grunt.
The more powerful of the diesels, fitted to the more expensive C250 d, is the same basic engine but it produces about 20 per cent more power again in all driving conditions, with the help of a second turbocharger. In real-world use, you could expect a C250 d to use more fuel than the C220 d if you took advantage of its greater performance.
The main reasons not to choose a diesel are aesthetic: you might prefer the generally cleaner environment of petrol pumps at service stations, or the generally smoother and freer feel of petrol propulsion. The diesels also have a particulate filter, which may clog if the car is used only for short trips.
Like the diesels, the two 2.0-litre petrol engines differ mainly in how much power they make and how much they cost.
The less costly petrol C-Class, the C200, is roughly equivalent to the C220 d for performance, and uses 6.5 litres/100km on the test.
The more costly, the C300, replaced the very similar C250 in August 2017. It is stronger than the C250 d and feels very responsive in most situations, without using much more fuel.
There are reasons you might bypass all of the conventional engines and instead choose the plug-in petrol-electric hybrid drivetrain that propels the most expensive Mercedes C-Class, the C350 e. High among them could be that you do a lot of driving in town, you have a secure garage where you can charge the car overnight, and you value its low-emissions, near-silent, progress in traffic.
You can drive a fully charged C350 e about 31km on its battery alone, Mercedes says – although our experience suggests 20-25km is a more accurate estimate.
Teamed with a 60kW electric motor in the C350 e is a turbo-petrol engine much like that in the C200. The combination of electric and strong petrol power makes the C350 e the most powerful of the C-Classes. However, the extra weight of the batteries and electric motor means it accelerates no harder than the C300.
If you want to drive only on the battery, the car helps you out. Resistance from its accelerator pedal gets stiffer as you push it down – it feels almost as though there’s a squash ball stuck underneath it. While you can push through that point easily and accelerate harder, you are reminded that to do so is to engage the petrol engine.
The C350 e returns the extraordinary low fuel-use figure of 2.4 litres/100km on the official test. Obviously, if you drive just on a charged battery it will use no petrol at all (but you will still have to pay for the electricity used when charging). On long country trips, where the petrol engine will be doing most of the work, you can expect fuel use near that of the C300.
Every Mercedes-Benz C-Class has an automatic transmission. The C350 e uses a seven-speed unit, and the rest have nine ratios.
Power outputs and all other Mercedes C-Class specifications are available from the Cars Covered menu, under the main image on this page.