Wow. Much ado about something simple. The question the OP wants to ask is: how efficient is regenerative braking? Forget about hills and up and down and all that. The answer is in general, normal driving conditions, including hills (not the most extreme ones) and regular braking (not race track level) regen is in my experience somewhere around 50% efficient.
Given the confusion in this thread, would you care to share how you calculated/measured that?
Thank you kindly.