On brake pads

So, here I am, waiting to have the brake pads on my car changed. 57,000 isn’t bad, I suppose. But it’s the rear ones that have gone. The fronts still have 20,000 miles on them.

It would appear that the rear brakes are used to put charge back into the battery. Which is good. Except that it costs £250 to change the pads.

I wonder how much fuel is saved by this energy regeneration?

Seems like it might be a false economy to me.