Mechanical Technology Archive

On 19 September in East London, Mercedes-Benz South Africa hosted a media launch for its new plug-in-hybrid range of vehicles, including the new C-Class C350e, which is to be built in the East London factory for local and export markets. Peter Middleton attends, drives the car and reports.

Mercedes C350e plug in hybridI have always been a bit sceptical about the notion that the rules for Formula 1 engines were to allow the technology to ‘trickle down’ to road vehicles. F1 motor racing is now using new hybrid power units with V6 turbo-charged petrol engines that produce 450-odd kW of power along with a supplementary electric drive adding a further 120 kW, when needed. The rules are designed to depend on the MGU-K for regenerating energy when braking and the MGU-H for efficiently managing the speed of the turbine shaft and regenerating power from it when the exhaust gas flow is high. If either one of these regeneration systems fails, the car immediately becomes uncompetitive.

Fuel use and maximum fuel flow are limited to a maximum of 100 kg per race and 100 kg/hour, respectively, making it impossible to sustain full boost – ‘hammertime’ – for more than a few laps per race. Overall success, therefore, depends on the car’s management system and the driver’s ability to balance deployment and harvesting of energy using strategies such as ‘lifting off’, or ‘coasting’ before braking into a corner.

On climbing into a Mercedes Benz C350e plug-in-hybrid however, the ‘trickle down’ effect from F1 becomes obvious.

Following the presentations and a lightning tour of Mercedes-Benz’s state-of-the-art C-Class factory in East London, pairs of media representatives were allocated a car, told that the GPS was programmed and that we were to meet up again at a restaurant 160 km outside of East London – ‘for a car and mode change’. 

The initial impression on getting into this C-class plug-in hybrid is its modern and luxurious feel. The first thing you notice is the tablet-like touch screen display in the centre of the console. Then, as you try to work out how to adjust the seats, where the hand brake is, what it might look like and how to start the vehicle, you sense an amazing level of sophistication.

“Driving the new C350e is just as easy as any other automatic vehicle from Mercedes-Benz,” the company claims. But having never driven an automatic Mercedes before, it took a while to locate the electronic brake release and park/drive selections.

Once moving, however, driving is not only easy, it is an absolute pleasure.

We managed to leave the East London manufacturing plant silently on electric power. We knew this, because the rev counter read zero for the first two traffic lights. At the third we were at the front of the queue and decided to try to get the engine to kick. We succeeded. The acceleration and responsiveness was amazing.

After a gentle drive out of East London, along with one or two ‘hammertime’ overtaking manoeuvres’, we started to play with the controls.

Fast facts: Mercedes-Benz C350e plug-in-hybrid

  • 31 km range in purely electric mode.
  • 60 kW electric motor produces a maximum torque of 340 Nm.
  • 2.0 ℓ four-cylinder petrol engine, produces 155 kW and maximum torque of 350 Nm
  • 205 kW and torque of 600 Nm available from both drives combined.
  • Certified consumption figures of 2.1 ℓ/100 km on the standard test.
  • CO2 emissions of 65 g/km on the standard test.
  • Equipped with Airmatic air suspension and a pre-entry climate control system that can be controlled via the Internet.

 

A switch between the seats changes the display on the touch screen from GPS mode to operating mode: This is mooted to “to influence the regulation between electric mode and the use of the combustion engine”.

In the Eco and Comfort transmission modes, the following operating modes are available:

  • Hybrid: All hybrid functions – electric, boost and recuperation – are automatically applied according to the driving situation and the route in the most fuel-efficient manner.
  • E-mode: For all-electric driving.
  • E-save: the charge status of the battery is maintained to allow all-electric driving at a later, more urban stage in the journey. Electric driving and boost are limited.
  • Charge: Allows the battery to be recharged while driving using the combustion engine.

In modes S+ and S, which we took to represent super sport and sport settings, hybrid operation is also active – with less priority placed on fuel efficiency, we assumed . In addition, there is an ‘Individual mode’ which makes available a comprehensive set of drive system settings – ideal for the Lewis’ and Nicos, perhaps?

It is very difficult to feel any change at all when switching between these settings, which is hardly surprising, on reflection, as they mostly optimise energy use rather than limit performance.

We also tried to experience a feature called ‘the haptic accelerator pedal’, mooted to help drivers reduce fuel consumption by providing feedback via pedal resistance. Neither of us could feel this resistance, but we later determined that we were in the wrong mode, it is only active in electric mode or in economy mode, when the Eco Assist function is active.

How does it work? When driving in electric mode, the driver's foot meets a point of resistance on the accelerator pedal when maximum all-electric performance is reached. Pushing through that resistance is like clicking ‘Yes’ to the question: “Do you want the combustion engine to kick in?” We were in Sports mode, so we were not asked this question. It would have been annoying.

A double impulse signal is also incorporated, which tells the driver to lift off the accelerator pedal to switch off and decouple the combustion engine from the drive train. This allows the C350e’s engine management system to automatically decelerate using data from the car's radar systems. We did notice some of this when our following distance decreased coming into a queue.

In support of anticipatory driving, the best strategy for efficiency, Mercedes has also enabled the navigation system to be connected to the engine management system. When an exact destination and route is entered into the navigation system, charge and discharge of the C350e’s high-voltage battery is controlled to ensure the optimal use of energy over the whole route – taking into account both stop-start portions of the journey as well as road elevation data.

Needless to say, the infotainment, comfort and safety levels are faultless. The vehicle has  Airmatic air suspension as standard with electronically regulated continuously variable damper adjustment; Attention Assist, which can warn of inattentiveness and fatigue; and Collision Prevention Assist Plus, which protects against collision at speeds of over 7.0 km/h and, if the danger remains and the driver fails to react, undertakes autonomous braking at speeds of up to 200 km/h.

The price? R804 900 – but the C350e is exempt from CO2 emission tax and comes with a six-year/100 000 km PremiumDrive maintenance plan.

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Contact Mechanical Technology

As from January 2017, Chemical Technology and Mechanical Technology have merged to form MechChem Africa.

 

Title: Editor
Name: Peter Middleton
Emailmechchemafrica@crown.co.za 
Phone: +27 11 622 4770
Fax: +27 11 615 6108

Title: Editor
Name: Glynnis Koch
Emailmechchemafrica@crown.co.za
Phone: +27 11 622 4770
Fax: +27 11 615 6108

Title: Advertising Manager
Name: Brenda Karathanasis
Emailbrendak@crown.co.za
Phone: +27 11 622-4770
Fax: +27 11 615-6108

 

 
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