It seems as though you have to treat the range figures on all EVs with quite a big pinch of salt, and the iX1 is no exception. The one I had was 98% charged and the range had dropped 100 miles when I returned it after driving just 50 miles.
BMW quote 268 – 296 miles for the edrive20. The models with the larger wheels like the M Sport, the lower range applies during optimal conditions.
Its a shame all iX1’s are fitted with a relatively small 65kW battery on all models. In comparison the Audi E-Tron 45 has a 77kW useable battery and Audi’s aclaimed 330 odd miles and much better torque. Just a shame about the interior!