My 75 auto does around 25/27 on the daily runs I do (12 miles in the am, same again pm), driving it 'normally'. I've seen it drop to 20/22 on the odd days when I've booted it a bit. And on an mainly motorway run down to Hendon and back recently, I saw 39, which was nice.
Oh, all verified with brim/brim technology!
Pete