Much less petrol consumption is a pretty good reason for choosing a motorbike or a scooter as petrol prices move on their inevitable accent towards mega-expensive.
What the actual numbers are we don’t know.
The bigger question is how do we make our roads safe for people choosing less fuel-dependent modes of transport such as bicycles motorbikes or scooters? How do we ensure that road design works well for them.
There have been complaints for example that traffic lights are designed to sense motorbikes and scooters reliably.