That seems like an unreasonably high level of confidence to have when paired with no supporting material.
A Model 3 has a battery no larger than 83kWh. A BMW i4 has a battery no larger than 84kWh. This car has a 101kWh battery. Considering the cars appear roughly approximately equally aerodynamic, it seems reasonable to expect the car with the 20% larger battery to be able to go about 20% further.