It's increadibly sensitive to your type of driving. Our current tank is showing 88mpg at the moment. That's on 196 miles so far, 82% of the tank remaining. A weekend away, just charging before we set off, about 300 miles of all kinds of driving from motorway to B roads to urban gave just over 50mpg. If you can charge at each end of your 30 mile commute I reckon you'll see 60+ unless you make regular use of the performance.
When running ours in, I kept it in Sport mode most of the time to make sure the ICE was running. Gave high 30s when doing that, which I thought was pretty good considering what I was doing.