well, i can confirm it makes a huge difference if you put into EcoPro and stick to it. The hard part is watching all the other cars flying by and not being tempted to boot it. I can do a trip from Bangkok to Hua Hin in around 2 hours. Definitely under 10 k/l. Last time I came back I did ecopro all the way and it resulted in 40mpg (around 14.5 k/l) for a trip of 87 miles. I used the ecopro analyser app on BMW connected which gives you all the details. Apparently I was in ecopro mode 97% of the time, Auto Start Stop contributed 19 minutes (i.e. glide mode or was switched off at traffic lights).
I have the ActiveHybrid 5 but to be honest I don't think it really helps that much in traffic. The battery is only good for about 3-4km before it switches back to the engine.