There’s no specific real-world mileage number published just for the R version yet (since it’s quite new), but we can infer it from the 390 Adventure:

* According to Autocar India, the 390 Adventure gave ~26.94 km/l in the city and ~35.50 km/l on the highway in their test.  

* Based on the R’s technical data (combined fuel consumption), KTM lists 3.4 L/100 km, which translates to about 29.4 km/l (theoretical) for the R.

* Real-world mileage will depend a lot on terrain: off-road riding, aggressive throttle use, and the extra suspension travel will probably reduce fuel efficiency compared to a purely highway ride.

Estimated real-world range: On a full 14 litre tank (spec for the R) — if you get ~29 km/l, that’s around 400 km per tank in ideal mix-conditions.