I have a 2003 E53 X5 diesel and do not do a lot of town driving, mostly from Hermanus to Cape Town which is a mix of 100 and 120 and i stick to the speed limit like glue. Filled up at Strand and drove to Bellville, back home, again to Bellville and back home with some driving around here. Done about 500km and the guage is still half (about 48l left in tank). Average on the BC says 11,2 km/l and it is quite accurate - have checked it against filling tank to tank) In town driving it will go down to about 9km/l. I drive like a 60 year old and try to get as much as i can from a litre of diesel. Try and mix 50 and 500ppm. Hope to go on a nice 4500km trip in two weeks time and will give feedback on consumption. I have often seen over 1000km on the range, especially on the open road! (Went down quickly and checked the distance and range - distance driven was 477km and range reads 639km)