The exact effect of AC of a car's mileage can not be said as apart from AC a lot of electric equipments work that consumes battery. Moreover, Tyre pressure, road/traffic conditions, driving style, etc. We have tested Tata Nexon EV in real-world conditions. You may check out our dedicated article by following the below link in order to get detailed information about its efficiency.- Tata Nexon EV Battery Draining First Drive Review
For this, we would suggest you walk into the nearest dealership as they will be the better people to assist you. You can click on the following link to see the details of the nearest dealership and selecting your city accordingly - Car Showrooms.