In brief
Propulsion, heating and charging are not completely independent users.
Useful to know
Bosch's Connected energy management coordinates the energy behavior of drive, heat system, power grid and charging. The solution can also use external cloud information. [1]
This is a broader task than showing the remaining percentages in the battery. For example, different modes may place different priorities on the available energy. The specific effect on mileage depends on the car and conditions, so there is no single universal saved value. When comparing, look at what functions are coordinated and when, not just the presence of a common "eco mode" sign.
Sources
For further detail and to check the information: