The latest edition of the Volkswagen Golf has been unveiled, and displays further examples of VW’s new direction towards electrification, heralding a new age of modern super-frugal mild hybrid powertrains. Despite outwardly only being billed as a facelift, the 2017 Golf is heavily updated from the current edition.
Visually, the most noticeable change is the modified cab – VW saying it has been “further honed”.
The new Golf has a freshly designed 48V petrol hybrid system as the main powertrain option, a strategy that could prove successful in the US, where Volkswagen’s ‘clean diesel’ aspirations look like they have fallen on deaf ears following the emissions scandal.
Aiming for a ‘real-world’ 60mpg, the new mild hybrid powertrain is modelled on the company’s turbocharged 1.0-litre three-cylinder petrol engine, with an added electrically driven supercharger and a combined starter motor/generator. An inexpensive lead-acid battery is used to harness and store recovered energy, for example from when the car brakes.
In contrast to regular hybrid transmission, which makes use of a full-sized electric motor, these 48V mild hybrids give assistance to the petrol engine by way of the oversized starter motor/generator. The belt that links the starter motor to the engine’s crank pulley is also used to assist the engine when additional power and torque are required. The procedure can be reversed to let the engine’s crank pulley to turn the starter motor/generator whilst the car is decelerating.
The energy recovered will be used for several other jobs, including powering a small supercharger that’s driven by an electric motor. By powering the blower using electricity, instead of engine and exhaust emissions, the car’s performance can be boosted from very low revs.
These two different types of electrical aid permit the engine of a 48V hybrid to be made noticeably smaller, allowing a 1.0-litre three-pot Golf to provide brisk performance and impressive economy.
Industry sources say the new 48V hybrid system will be able to compete with a modern EU6-rated diesel engine, due to the fact that it doesn’t use a full-size electric motor or an expensive lithium-ion battery. This is made all the more relevant with VW announcing that expensive urea injection systems are probably going to be used on Golf-class diesel models.