Fuel consumption: Mercedes Benz C180 - 1595 cm³

In 2011 Mercedes Benz introduced a facelift for its current C-class, the W204. With stricter CO2-regulations and company policies in place, downsizing is a major trend with car manufacturers. Between 11/2009 and 04/2012 the C180 had a 1796 cm³ engine, but after 04/2012 it had been downgraded to a 1595 cm³ engine, in order to cut emission and reduce fuel consumption. 

Guitigefilmpjes has hit the road in order to see how the fuel economy is and if this engine lives up to its expectations. Technical details about this engine type can be found below:

Engine: M 274 DE 16 AL 4-cylinder petrol engine (1595 cm³) 

Transmission: 6-speed "Agility Control" manual transmission
Performance: 156hp / 250nm
0 to 100km/h: 8,5sec
Top speed: 225km/h (140mp/h)
Fuel tank (US gallons): 59 liters (15.59 US gallons)

In the picture below, the ECO-mode had been engaged which enables the auto-start stop function (when standing still). The driving profile was trimmed perfectly to cut fuel consumption the most, driving almost the while trip on a secondary road at a maximum speed of 85km/h (53mp/h) with only a few stops and accelerations, combined with a few kilometers of light city traffic.  

After having drivin about 66 kilometers (41 miles) the onboard computer displayed an average consumption of 5,5l / 100km (42,77 mpg US). Considering that the fuel consumption for this route is specified by Mercedes Benz at 4,7l / 100km, the result is merely 0,8l / 100km off. 

As this result has been achieved by trying to drive as economically as possible under the best circumstances (almost no braking + acceleration) I think that it is not possible to reach the figure of 4,7l /100km. 

The second picture displays the average fuel consumption for several trips combined. The driving profile was divided by 15% Autobahn (fast), 40% highway, 10% inner city and 45% secondary road using the `normal` driving mode. 
After having drivin about 2791 kilometers (1744 miles) the onboard computer displayed an average consumption of 7.0l / 100km (33,6 mpg US). Considering that Mercedes Benz states that its average consumption for a combined driving profile is 5.8l / 100km, the gap widens as `heavier` driving conditions (lots of braking and acceleration in the city, fast runs on the Autobahn) prevail.

Final thoughts: 

On paper the downsizing trend looks fine, emissions and fuel consumption are reduced, while performance stays the same or is slightly increased. However, the engines are optimized to perform the best during the test cycle, which often does not match realistic driving conditions. Therefore smaller engines do not automatically mean lower consumption, on certain conditions a larger engine can be more economical due to the fact that it does not have to develop so much power to match the same performance.

Hence, on paper the new 1595 cm³ C180 will only match the 1796 cm³ C180, not making any  noticable difference. 

Previous Fuel Consumption reports:

• Audi A4 2.0 TDI / Audi A6 3.0 TDI / Mercedes Benz E220 CDI
• BMW 530d xDrive / Mercedes Benz C220 CDI
• Mercedes Benz C180 / VW Passat 1.4 TSI / BMW 520d Touring
• Audi A6 3.0 TDI 204hp (MY2012 / C7)