[Stubby79]

OP: You're mixing up "Power" and "Energy", mathematically. It doesn't work that way.

Correct me, if I'm wrong.

Had time to look it up.

Power P (watts) = M·v·a (mass · velocity · acceleration)
Mass in KG.
Velocity in meters per second. (the change in speed, be it 0 to 60mph or from 50 to 40mph)
Acceleration in meters per second squared.

Energy is the capacity to do work. Energy is power integrated over time.

Power is the rate at which work is done, or energy is transmitted.

Energy = joules = watt-seconds

Power = watt = joules/second

Point being that it takes the same amount of power to accelerate from 0 to 10 mph in X seconds as it does from 40 to 50 mph in the same X seconds. And the reverse is true for braking/regen, from 50 to 40 is the same as 10 to 0.

You get more regen braking force at higher speeds either because you have much more voltage being generated (therefore you can suck more watts out of the motor) at higher rpm, or because the inverter is programmed to brake less at lower speed and/or is programmed/limited/designed to how many amps it can suck out at any given moment (amps x volts = watts).