Is your Fabia the first generation or the current gen model? The eco model you're referring to is the
Greenline, which is basically Skoda's version of the Polo Bluemotion and SEAT's Ibiza Ecomotive.
From the reviews I've read (like the one above) it seems essentially pretty similar to those models which means it shares the same "problems" (my use of quote marks - I sometimes think the magazines miss the point of the eco-orientated models) - such as quite long gearing having to cope with a low power output, average performance etc, plus the Skoda doesn't dip below 100g/km of CO2 (which is necessary to qualify for free road tax in the UK) like the VW and SEAT do. Perhaps it's inherently less aerodynamic.
If yours is the older shape Fabia though you probably won't be able to just chop and change bits from the Greenline and will probably have to DIY any aeromods. What you could try doing is changing to some low rolling resistance tyres, which I know is one thing that the Greenline uses.
You're getting great figures from it though, especially for cold weather and snow on the ground. It's essentially the same engine as VAG uses in all it's small eco cars so it's definitely a good'un.