You can recapture 90 percent of the power normally lost to heat in braking. But you only get back about ten percent of the power you used to achieve the speed you brake from. And, of course, the longer the trip before you brake, the lower that percentage is. I suppose you do get something back, but in the grand scheme it’s a rounding error.
You’d best use an MC Escher sort of route where you’re always driving downhill :)
You’re right about that. MPG for self-charging EVs is better in the city than on the highway. When I saw that on a car’s sticker once I was totally surprised, but it makes sense if you get some bang for the buck when braking however small.