Volkswagen is claiming to have introduced the world's first cylinder shut-off system for a high-volume production, four-cylinder TSI engine. The new unit will become available in 2012.

As with systems fitted to larger, multi-cylinder engines the idea is to save fuel by shutting off a number of cylinders - in this case two - under low to medium loads. According to Volkswagen the system is worth between 2- and 3mpg on the European combined cycle. The fuel saving is said to be even greater at constant, moderate speed.

The TSI motor with cylinder shut-off will also meet future EU6 emissions standards. Volkswagen claims that efficient, low-emissions driving does not result in excessive noise or vibration.

Shut-off works at engine speeds between 1,400- and 4,000rpm and torque outputs of 18- to 55lb.ft. Apparently nearly 70% of the EU driving cycle takes place under these conditions. A sensor on the accelerator pedal controls when cylinders two and three are deactivated. When the pedal is pressed sufficiently all four cylinders are activated and the software is supposed to suppress the shut-off function when driving in a sporting style or, somewhat unusually, on roundabouts.

It's likely that the new TSI engine will see service in the next generation VW Polo and the just-launched VW up!.

John Lambert - 5 Sep 2011