Hi Fredrick,

The 1.6 TDI Passat is simply amazingly economical. I once got one to go from Galway to Glasgow and back on one tank of fuel, and that economy is its greatest asset. It's also very comfortable, well made and nice to drive. 

The Mazda simply can't match that kind of economy, but then it has a much more powerful engine and is much more overtly sporting to drive - both in terms of its engine and its handling. 

The Passat has a nicer, more upmarket feeling cabin, but the Mazda would probably be more reliable in the long term.