Mercedes-Benz C 300 de real-world fuel use
How much is really driven with the engine off
When not driving on battery alone, this model uses about 6.6 L/100 km. Its official electric range is 78 km. Charge more often and your figure drops towards the official one — try the calculator.
Against similar plug-in hybrids
The closest models by kerb weight in the same data.
| Model | Official → real | Real L/100 km | Engine off | Cars | Gap |
|---|---|---|---|---|---|
| Lexus NX 450h+ | 4.8 | 34% | 2,503 | 4.7× | |
| Mercedes-Benz C 300 de | 5.3 | 19% | 6,926 | 5.8× | |
| Volvo V60 | 6.0 | 27% | 37,406 | 5.4× | |
| Volvo S60 | 6.0 | 28% | 3,304 | 5.1× | |
| BMW 530e xDrive | 6.9 | 22% | 7,725 | 3.9× | |
| BMW X3 xDrive30e | 7.1 | 24% | 17,653 | 3.5× | |
| BMW 545e xDrive | 7.6 | 24% | 1,529 | 4.0× |
UK company car tax
Benefit-in-kind tax is based on the official CO2 figure (24 g/km average for this model in the data), not on real-world use. Plug-in hybrids approved to the stricter Euro 6e-bis standard show higher official CO2. Under HMRC's current easement, qualifying cars first registered from 1 January 2025 to 5 April 2028 with official CO2 of 51 g/km or more and at least 1 mile of electric range are treated as 1 g/km for company car tax. Check your own car's emission standard and figures before relying on it.
What the rule change meansOwn one? Send us your real figures
Tell us your average fuel use, how often you charge and your typical trip. Owner reports will appear separately from the official data.
Questions
How much fuel does the Mercedes-Benz C 300 de really use?
Across 6,926 cars in the EEA 2024 fuel meter data, the Mercedes-Benz C 300 de used 5.3 L/100 km (52.9 mpg UK). Its official figure, derived from WLTP CO2, is about 0.9 L/100 km.
Why is the real figure 5.8× the official one?
The official test assumes a high share of electric driving. In real use these cars covered 19% of their distance with the engine off, so the engine ran far more than the test assumes.
Where does this data come from?
From the on-board fuel consumption meters fitted to every new car in the EU since 2021. The European Environment Agency publishes the readings each year under a CC BY 4.0 licence.
Can I get closer to the official figure?
Yes, by charging before most trips and keeping daily journeys within the electric range of about 78 km (official). Use the calculator to see your own likely figure.