Dear Sir or Madam.
The following link leads you to the official press kit, where you can find all information about the new Audi RS 6 Avant.
https://www.audi-mediacenter.com/en/fourth-generation-audi-rs-6-avant-11975
Fuel consumption of the models listed
(Information on fuel consumption and CO2 emissions as well as efficiency classes in ranges depending on the tires and alloy wheel rims used)
Audi RS 6 Avant
combined fuel consumption in l/100 km: 11.7–11.5 (20.1–20.5 US mpg)
combined CO2 emissions in g/km: 268–263 (431.3–423.3 g/mi)