What you are postulating is that "low" setting is better than "standard" regen in terms of range and efficiency (but no regen is best of all)?Overall, coasting (no regen or power) is most efficient. Why? Regen does not recover all momentum. Due to inefficiencies (in charging using regen and then in reusing that energy for driving the car) I speculate that you only see about 60%. So coasting, you get to use nearly 100% of the momentum to move the car. Regen is not a bad thing it's just not as good as coasting.