Volkswagen is currently running a twenty strong test fleet of Twin-Drive Golfs in and around Berlin Germany and the results of this work are expected to hit the retail market around 2011. The current test models are using diesel
engines but the production versions are likely to switch to gasoline when their 30-mile electric range has been expended. With coming EURO VI emissions standards that approach the U.S. Tier 2 Bin 5 standards, a diesel hybrid would simply be too expensive to be commercially viable. The drivetrain layout of the Twin-Drive is different from the approach being used by current parallel hybrids
or extended range EVs like the Volt
. While the Volt ER-EV is a series hybrid setup where only the electric motor is mechanically coupled to the wheels, the Golf is a parallel system but without a transmission. The single reduction gear ratio is comparable to a normal high gear and the torque of the electric motor is used to provide the equivalent of the torque multiplication that is normally achieved with a lower gears. The absence of a conventional gearbox compensates for some of the added weight of the battery and motor. A 12 kWh Sanyo lithium ion battery pack provides 30 miles of driving range and energy storage from the regenerative braking.
[Source: Motor Trend