That doesn't surprise me at all, My Yaris d4d will get 70mpg without too much effort at 60mph on a run, and that's 11 years old now already, and has become more economical with age I think.
The main benefit here is that this is an example where good mechanical engineering proves that aggressive weight reduction is not necessarily the most important factor to fuel economy. There is a magical mix of optimal gearing and torque that some diesels achieve (again by good design), leading to incredible real world fuel economy - and the lack of needing to concentrate too much, unlike a hybrid.
I have been saying that the 1.6 Civic tourer DTEC is probably the finest car on the market for a while now, it's a genuine all-rounder, and likely future classic (if the old Accord Aerodeck was anything to go by). Unfortunately the EU seem to be set on targeting and taxing everything diesel, so I doubt there will be any renaissance with a huge amount of longevity.
I would have one now, but I wouldn't spend £20K on a family car. Once they are down to £8-10K I may consider it.
There is one issue that is never mentionned, and that is that while the DTEC might trump any hybrid on the motorway, it wont in town, and modern diesels with particulate filters (Euro 6 complaint ones more so), are not suited to sustained urban use at all - whereas a hybrid is happy wherever.
Also, consider the price premium for diesel, and you can drop about 8-10mpg off that, and diesel is likely to be subject to increasing tax in the future.
... all that said, that's a lovely car, and I would swap the I2 in for one any time.
For our friends accross the pond: http://en.wikipedia.org/wiki/Europea...sion_standards
Though it's a load of figures, the attainment of particulate and NOx compliance for diesels has been a major headache for manufacturers, and many have not produced reliable options due to the particulate filters now fitted.