The factory recommendations are not always the maximum theoretical distance you can get from your cars, those recommendations are based on real world usage, e.g

The factory recommendations are not always the maximum theoretical distance you can get from your cars, those recommendations are based on real world usage, e.g. 120 km/h on a highway or 30km/h average with stops in the city center. It is called "hypermiling", you can do that with gas cars as well, by driving on a level road, minimal breaking and accelerating, plus driving in the engine's optimal RPM period in the highest gear possible. In short, the ideal conditions for the car.