The road to electromobility leads across a technological bridge on which the best attributes of two technologies are combined into a new, environmentally friendly drive concept. It is of course much too early to bid farewell to the internal combustion engine. But in the future, this well-proven drive technology of more than 130 years standing will have to share the space under the bonnet with one or more electric motors if the emissions limits prescribed by the EU Commission are to be complied with. Mercedes-Benz already reacted in 2014 by bringing the first model with plug-in hybrid technology to market. In 2015 this was followed by two further models, and by 2017 nine more models are to be available with this drive system.
In plug-in variants, an internal combustion engine is combined with an electric drive system in such a way that the most economical of the two is used from case to case. Unlike a conventional hybrid, such a vehicle is able to cover longer distances purely under electric power, and therefore with zero local emissions. In the case of the C 350 e this is around 30 kilometres, even in the dense traffic of a large city like Berlin with its numerous strangely phased traffic-lights. At first and even at second glance, the plug-in hybrid version of the C-Class is hardly different from the conventionally powered model variants. At most the new model designation with an “e” for electric drive, the discreet charging flap in the rear bumper and a few blue accessories identify the saloon as a representative of the new drive generation, which enjoys a buying subsidy of 3000 euros in Germany.
205 kW powerpack
Under the bonnet a turbocharged two-litre, four-cylinder petrol engine and an electric motor are combined to form a 205 kW powerpack capable of a top speed of 250 km/h and acceleration from zero to 100 km/h in 5.9 seconds.So much for the conventional data from the fossil age of automobility. Much more interesting for the current discussion on mobility in an era of climate change are the other values of the C 350 e. The electric operating range of around 30 kilometres is totally adequate for most commuters to reach their place of work and return home in the evening with no local emissions.
According to employment statistics from the Federal Statistical Office in Germany, around 49 percent of employees live less than ten kilometres from their place of work, 27 percent live up to 25 kilometres away and only 17 percent need to cover more than 25 kilometres. The purely electric range is however only one aspect of the environmentally friendly technology. At least as important is the proportion of kilometres covered without use of internal combustion engines that can be achieved by the use of hybrid technology. In a specific case 576 of 2867 kilometres were covered without an internal combustion engine, and therefore without emissions. A respectable proportion of around 20 percent.
Recharged in two hours
The energy for the electric operating range is supplied by a 6.4 kWh battery discreetly and space-savingly located over the rear axle – it comes from the company’s own production facility in Kamenz, Saxony. Under ideal conditions it takes two hours to recharge the battery after the charger cable has been plugged into the socket or charging station. Charging can also be controlled by setting the departure time using the Mercedes connect me web app.
Once the ignition key has brought the drive unit to life – nothing happens at first. A discreet “ready” informs the driver that the journey can begin. As is usual for hybrid models, the C 350 e starts silently in E-mode and then changes to engine mode depending on the mode selected and the state of the battery. Three other settings are available apart from Hybrid, where the vehicle constantly changes between electric and engine operation depending on the driving style. E-mode stands for battery-electric drive, which is particularly suitable for city traffic if the driving style is predictive and the opportunities for braking recuperation are used.
The battery is charged when braking
When conventional vehicles are braked they generate heat. Hybrid models convert the energy thus obtained into battery power. This technology uses its full potential on motorways, charging the battery whenever the vehicle is braked. In E-mode the pressure-sensitive accelerator pedal also helps to ensure eco-friendly driving. A pressure point indicates the limit of electric drive. If the accelerator is depressed beyond this point, the four-cylinder engine takes over the power delivery. Electric driving is possible up to 130 km/h, after which the engine takes the main role.
In cities the silent drive system always takes pedestrians by surprise when the saloon approaches without the familiar engine noise. A defensive driving style is therefore recommended, and this also helps the energy balance.
Classic qualities of the C-Class
When the E-Save setting is selected, the electric charge is maintained for later, for example when intending to drive through an environmental zone. In this setting the electric drive is only available to a limited extent. If “Charge” is selected, too much electrical energy has clearly been consumed during a journey and the battery is charged for a drive through the inner city. In this setting the internal combustion engine remains switched on, and this may increase fuel consumption.
It all sounds very complicated, but it is not. After a brief familiarisation time, the C 350 e shows the classic qualities of the C-Class – comfort, serenity and stable handling. A display also keeps the driver constantly informed about what is happening: whether the battery is being charged, the engine alone has taken control, the car is travelling in E-Mode or it is being moved by a mixed double of electric motor and engine power. The transition between the different drive combinations is so smooth that neither the driver nor the passengers notice which variant is providing power at any given moment.