economy

Being new to MB's I am not sure whether I should be driving in the standard or economy setting on the auto box can someone enlighten me please :D I normally use economy on the motorways.

Thanks to all of you who gave your input last time, esp Richard, Brian & Dieselman. I've now had a chance to take my baby on a longer trip - to Windsor & back on the M40 - 240 mile roundtrip @ 75mph-ish and probably incorporating c20-30 urban miles. Overall, I achieved 40mpg. Now, is that...

I've now had my '03 E270CDI auto for a month and covered ~900 miles. However, the MPG is somewhat less than expected - I'm getting 18-23mpg urban and 38mpg is the best I've ever achieved cruising at 60mph, despite driving like a nun. This is significantly down on MB figures (29 urban, 52 extra...