I don't know about maximum regeneration but the regenerative system seems very efficient to me. We live in a valley and I drove to the top of the hillside, which is in two shelves, then I went about another 1 or two Km's beyond to get to the store. I started out at 70 km range and drove gently but at the speed limit up the hills and on the flats, getting down to 66 km range. I then used the regenerative break hand pedal as much as I could driving back home, and I got back to my starting 70 km range. I know the car cannot defy the laws of thermodynamics but it seems like I got back at least 75 percent or more of the energy.