I'm coming to the conclusion that book MPG should be possible on a reasonable round-trip, say 25 miles, but it does take an acceptance that you need to drive SLOW. I'm finding a few percent over book is possible this time of year.
For example, 76mpg in the daily commute in my 'dismal' 500 (as Maxi calls it!), book is 67mpg of course. In winter it's considerably lower, and the DPF regens hurt it too. In my other car, a 1.2tsi (petrol) Skoda, with 1,500 miles on the clock I'm getting ~53mpg on the daily commute (book is 49mpg).
My only reservation is that the figures might be skewed for those models with start/stop, since that artificially (IMO) inflates the quoted MPG.