48-volt mild-hybrid Volkswagen to introduce technology

THE backlash against diesel car engines is really gathering pace, and if you need evidence, the announcement by Volkswagen that it’s going to start introducing 48-volt mild-hybrid powerplants as a fuel-efficient alternative to diesels should do the trick. The first VW to feature such a propulsion system will be a Golf-sized model, although other vehicles in the Volkswagen range are likely to be getting the systems in the near future.

Frank Welsch, Volkswagen’s head of development, recently said, “Once we have it in an MQB*-based model it’s more or less plug and play.” Welsch has also been reported as commenting on the sidelines of the press launch for the new VW Polo last month, “We can put it on other models because we have a modular platform.”

The MQB platform – Modularer Querbaukasten (German for “Modular Transversal Toolkit” or “Modular Transverse Matrix”) – is the base for a number of Volkswagen models that range from the sixth-generation Polo subcompact that enters the European market in the autumn to larger compacts such as the Golf Hatchback and Tiguan crossover. It also underpins plenty of models from VW’s other brands, including the likes of the Skoda Octavia and Seat Leon compacts.

Manufacturers are increasingly adopting 48-volt systems for reasons of fuel efficiency as diesels are facing a backlash from consumers and governments due to their levels of toxic nitrogen oxide (NOx) emissions. Renault is another manufacturer also embracing the technology by offering it for its latest Scenic minivan.

It’s actually smaller diesel engines that are feeling the heat most as making them compliant with ever-tightening emissions regulations is proportionately more expensive than it is for larger units. For example, Volkswagen has added selective catalytic reduction (SCR) systems to the two 1.5-litre diesels it’s going to offer in the new Polo. Vicente Franco, a senior researcher at the International Council on Clean Transportation, says adopting SCR adds around €200 to the cost of a diesel. However, VW’s Welsch claims that adding aftertreatment systems to diesels adds something like €600-800 in material costs.

For the record, a mild hybrid is much more like a regular petrol engine than a full hybrid as the electric motor does not propel the vehicle on its own as it can and does in a full-blown hybrid. In a mild-hybrid system the electric motor is only there to assist the petrol engine to deliver better fuel economy.