[rad_gruchalski]

Where can one find the actual method used to come up with this number?

Is it the difference in tickets sold during €9 and prior to €9 * statistical distance travelled by a statistical German assuming that every surplus ticket sold was bought to substitute a car travel?

Subsequently, it would be great to have that number put in context right next to a graph showing gasoline and diesel sales in the same time period. Those were also cheaper for the same time period.

[advisedwang]

This data comes from a survey (see [1]). The CO2 figure is "Based on the journeys shifted from cars to buses and trains" [2].

[1] https://www.vdv.de/bilanz-9-euro-ticket.aspx

[2] https://www.vdv.de/presse.aspx?id=df893fc7-1759-497b-9488-ce