Regenerative braking improves efficiency even without careful driving, additionally you can drive carefully and improve your efficiency even more. This isn't the same as suggesting current regenerative braking isn't "good enough" for start stop applications.
Braking will always involve energy loss, that's just physics. Over time we can improve how much energy is regained during braking but again that it can be better does not prove that it's not worthwhile now.
I've never said it doesn't help. When the bar is in the right section, that means that your regenerative braking is operating at peak capacity, with extra friction braking applied on top.
> Braking will always involve energy loss, that's just physics. Over time we can improve how much energy is regained during braking but again that it can be better does not prove that it's not worthwhile now.
The energy loss of regenerative braking is some XY%. The energy loss of friction braking is 100%.
The optimal way to drive with regenerative braking is slow and steady braking. So that you are eating XY% energy loss in your braking energy, and not "Partially XY%, partially 100%". Most people drive in a way that would put them in the latter category.
As another poster mentioned, its quite possible for cars with $10,000 batteries to usefully absorb more energy through their regenerative braking.
I'm not really sure what your point is or where your comments fit into this conversation at this point.
When you hit the brakes on a regenerative-braking hybrid, you will see a bar start to fill up. The bar is divided into two sections.
If you tap the brakes, the bar only fills up a little, and stays in the left section. That means that your regenerative brakes are slowing you.
If you slam the brakes, the bar fills up fully, and is way in the right section. That means that your friction brakes are slowing you.
If you drive 'normally' - like most other people drive, you will never keep the bar in the left section during braking. It will always be half-way in the right section. This means you are wasting ~half of your braking energy, as friction and heat.
If you drive very smoothly, with no sudden braking, you can keep the bar almost constantly in the left section. But this requires you to start braking a lot earlier than most drivers, when you see, say, a red light.
This isn't a bad thing, since smoother acceleration/braking reduces traffic jams, but it's not how most people drive.
In practice, I have observed that the difference between these two forms of driving (Aggressive braking + accelleration, smooth braking + accelleration) is the difference between ~43 MPG and ~48MPG.