I would have thought regenerative braking could be disabled by simply electrically isolating the motors. You still have the mechanical resistance of turning the rotor, but I would also think that is easier than turning over an IC engine.
What I'm wondering now is, if "free roll" mode is activated while I'm at a red light... is there a chance I start rolling as I do in my manual when I take my foot off the brake?
Maybe I should just reach out to Tesla at this point though (-:
Isn't this exactly what regenerative braking is? There's no mechanical disconnect between the wheels and the motor (i.e. a clutch) so pushing the car essentially turns it into a generator.
Inside the motor/generator, what happens is that if there's current flowing in the windings as a result of the EMF induced by turning the rotor, then, loosely speaking, it creates a magnetic field which opposes the rotation - but if it is not connected to some load (or a short-circuit) there's no current, even though there is still an induced EMF.
It's a standard case of the conservation of energy - if it were not the case, you could put an arbitrary number of generators on the same shaft, all supplying power to external loads, and then use the output of a couple of them to power a motor spinning the assembly...
If you are turning a motor/generator slowly, then the difference in torque is not much, but I am responding to the implication that the motor would have to be mechanically disengaged in order to disable the braking effect.
And, off the top of my head I'm going to say the manual locking hubs will be better overall. Better from an energy efficiency perspective as well as overall convenience and simplicity of design. They might be worse for Tesla's P&L though since anyone with a tire jack and a standard parts dealer nearby could work on the car.
Then again, besides the fact that I'm a cynic... what the heck do I really know!??!