Having just finished my first tank of juice I feel am now qualified to post on this thread
Despite an initial trip from the garage I purchased the car from at over 50mpg, on the tankful since then using the brim to brim technique I have averaged 41.57 mpg, the OBC gives a figure for the same distance of 40.9 mpg.
This is in a 2007 (Pre ED) E91 320d on Tesco's finest. My main journey is an 8 mile commute each way every day with a little duall carriageway followed by b road and then stop start in town.
Was hoping for a little better but we'll see how we go. I have just started using some Millars additive as I don't use expensive diesel so interesting to see if it makes any difference over the next few tanks....
