I average 40-45 on a run, going up to low 50's on all day tours/motorway use over the last 7 years. If its the newer model they are supposed to be a bit better than that but there's probably not much in it.
I tend to fill around 180ish as its a pig to push when you run out (205 and it was dry at 75mph in the outside lane in rush hour traffic...).