It would hurt the brand to cheat the sat-nav based range, it would mean the car wouldn’t make it to a charger when it said it would. You’d have a lot of unhappy customers.
Think of the sat-nav range as closed-loop and the other testing based ranges as open-loop.
This is accurate to me within about 5% of the battery, even driving at fast highways speeds and in cold weather.
If it was "cheating" I think I'd notice an issue when the car said I had 5% left but the real battery charge was empty.