The Volkswagen Golf's new petrol engine is as efficient as a diesel

By CARSIFU | 20 March 2018

WOLFSBURG: Volkswagen has developed an engine: the new 1.5 TSI ACT BlueMotion with an output of 130PS and is currently already powering the Golf.

Volkswagen claims this petrol engine is like no other before it: a petrol engine that offers diesel-like fuel economy but is significantly cheaper to buy and on a journey occasionally switches off two of its four cylinders or even takes a complete break.

In the future, the efficient 1.5 TSI ACT BlueMotion will also be available for other Volkswagen models.

The combined fuel consumption of a Golf 1.5 TSI ACT BlueMotion is just 4.8 l/100 km. Volkswagen achieves this benefit through the new TSI Miller combustion process and the use of a high-tech turbocharger with variable turbine geometry (VTG).

Whenever possible, Active Cylinder Management – called ACT for short – deactivates the two inner cylinders. It always does this at times when power demand is low.

The deactivation function operates within an engine speed range of 1,400rpm to 4,000 rpm and at vehicle speeds up to 130kph.

The driver is made aware of the barely perceptible changeover from four to two-cylinder operation by the "2‑cylinder mode" notification in the instrument display.

The 1.5 TSI ACT BlueMotion achieves an extra level of innovation when combined with the seven-speed DSG dual clutch gearbox.

As soon as the driver lets the Volkswagen 'coast', i.e. predictively releases the accelerator pedal for conditions ahead or is going down a slight slope, the engine management system switches off the TSI completely and decouples it from the drivetrain by disengaging the clutch.

In this phase, the engine no longer needs to be "dragged along"; the use of the vehicle's kinetic energy is thus optimized.

In parallel with the cylinder deactivation and complete engine shut-off, a further feature of the 1.5 TSI ACT BlueMotion is the previously mentioned new TSI Miller cycle combustion process.

This entails the use of optimized valvetrain control (early closure of inlet valves) – combined with higher compression and turbocharging.

It innovatively controls combustion of the fuel and air mixture, which leads to an improvement in efficiency of up to 10%.

Within the foreseeable future, Volkswagen will be launching further derivatives of the 1.5 TSI ACT BlueMotion in global markets.