Does the nav system do a good job of compensating? The "normal" display on the 3 is based on the EPA rating and is always wrong, but when I navigate, I find the trip range thing to be quite accurate -- even factoring in upcoming hills and traffic.
The energy app shows you live estimates based on distance, elevation, wind speed, temperature, humidity, tire pressure, cabin climate load, and even your phone charger.
As a rule of thumb I halve the EPA estimate in winter and 2/3-3/4 it in summer.
I have had no range issues doing this for the 130000km + I have owned the vehicle.
Edit: If I'm going to tap, I check the Wh/km, as that is what I'm used to. It was better before they removed it from the swipe, but hey, we gotta fill those sprints somehow.
Average over 130000km (3y) is 191Wh/km
Winter can be as bad as 330Wh/km (-30C 110km/h)
Summer can be good, but I've never seen a 100km trip better than 145Wh/km.
Generally the lower the remaining range, the better the EPA range (estimate) is.