The Volkswagen Auto Group is pouring in more resources for greener engines with the introduction of a mild-hybrid and bi-fuel powertrain. These engines will make their way to the recently unveiled updated Golf and the next-generation Polo.

For the micro-hybrid system, it will be installed in select variants of the 2017 Golf with the new 1.5-liter TSI engine. Friedrich Eichler, Head of Volkswagen Powertrain Development, describes the engine as a “Partially and fully electric drive system to form a key pillar of our drive system strategy ”. It features a Coasting – Engine off Mode which the automaker says “represents a low-cost level of electric-powered motoring on a 12-volt basis”.

Volkswagen ushers in two green engines for Golf, next-gen Polo

The 1.5-liter TSI engine is paired with a compact lithium-ion battery. It then powers the 12-volt vehicle electronics, with the battery supplying the electric consumer units with power when coasting. Power is managed by a Q-diode and regulates current flow between the lithium-ion and lead-acid batteries. The system can work at speeds up to 130 km/h and allows the car coast with the engine completely deactivated when there is no throttle input. Also present is a two-cylinder mode to cut down on fuel use. Volkswagen claims a fuel economy gain of approximately 2 kilometers per liter.

Volkswagen ushers in two green engines for Golf, next-gen Polo

Moving to the 1.0-liter Bi-Fuel engine, it packs three cylinders, a turbocharger plus the capacity to run on both gas and compressed natural gas (CNG). Volkswagen boasts that this TGI engine has its own system that is able to convert methane more efficiently. It works when the engine is running warm or under low load and makes one cylinder rich and another cylinder lean. During the cycle, it generates more steam to convert to methane. In this configuration, it puts out 90 PS.

These micro-hybrid Golf will be available by the third quarter of this year while the Bi-Fuel Polo may be revealed a few months after the all-new model debuts next month.