The philosophy of ‘down-speeding’ is fully employed through the fitment of gear ratios more normally associated with turbocharged diesel engines.

Successful down-speeding relies heavily on the immediate availability of high torque levels at very low engine speeds in response to driver inputs. The integration of CPT’s variable torque enhancement system or VTES supercharger technology virtually eliminates all perceptible turbo-lag even in the absence of variable geometry turbine technology normally fitted to turbocharged diesel engines. Through careful integration of the above technologies and the implementation of engine stop-start and smart alternator control, AVL is able to demonstrate CO2 emissions of just 159g/km for a Volkswagen Passat demonstration vehicle at 1,590kg vehicle mass, which also meets Euro 5 emission standards. By way of comparison, a series production Passat emits 165g/km when fitted with a 2.0l TDI (167bhp) diesel engine and 194g/km when fitted with a 2.0l TFSI (197bhp) petrol engine.

At the same time the 197bhp engine delivers high levels of performance and refinement while VTES ensures outstanding transient response even at the lowest engine speeds, equivalent to a naturally aspirated engine of twice the capacity.

“Getting a petrol engine to deliver the lower CO2 emissions of a diesel engine is something of a holy grail for the motor industry,” says Nick Pascoe, chief executive officer, CPT. “The challenge is to retain the driveability at low engine speeds in order that drivers can fully realise the benefits of down-speeding. An electric supercharger can react instantly to these transient load conditions, delivering up to 25kW of additional power at the crankshaft in less than a second.”