Hi there.
It depends on how much fuel you put in. Let me explain. The extra km's will increase and peak until it equals your fuel range, from where it then keeps on going down with your fuel range. I normally put in R400 and the most I got was 127km extra km's on EcoPro. On one occasion I put in R500 and I got 145km extra km's on EcoPro. Thus, the more fuel range you have available, the higher the peak extra km's is possible. Hope this makes sense. I must admit it is sometimes difficult to keep it in EcoPro but the extended km's makes it worthwhile.
BTW, I drive a 2012 F30 320i manual and I use the car daily to work and back on a quiet road, roughly 65km's per day.
Regards,
Salwynne