“All the advantages of a hybrid in the city, and the advantages of a diesel on the highway…” - Demosthenes X
When Honda and Toyota introduced gas ICE/electric hybrid cars, German automakers sneezed at them. Instead they spent a lot of money in developing cleaner diesel ICE. At that time the question was EITHER gas/electric hybrid OR diesel. Now, after looking at the success of the Prius, they belatedly are trying to join the party.
Is the diesel/electric hybrid a good idea? Not so much as for gas/electric. For a given power a clean diesel engine is more expensive to make, and possibly heavier. Another point is that you do not get much benefit by shutting off the diesel engine at stop signals in the city, since it is already a fuel sipper when idling (very lean burning). The parallel hybrid is more suitable for gas/electric combination because the high torque nature of the electric motor complements very well to the weak torque of the gas ICE at low rpm, thereby allowing the use of high-efficiency design like Atkinson cycle.
113mpg (100km/2.5 litre)? That’s amazing! Does VW take fully charged Li-ion cells (by the plug-in feature) into this number? A 1500cc TDI alone won’t give this kind of mileage even on highways.