Potential buy Audi A8 3.0 tdi 2006 thoughts

[brabus]

Evening. I drove the above the other day and was a little concerned or maybe its the charactersistics of the vehicle? when steering at a lower speed it becomes a bit harder where as a drive on the dual carriageway the steering is lighter. Is this how the steering is supposed to behave?

Secondly the car is a 2006 would the vehicle have dpf?, a vin check shows its Emission standard, EU4, DPF preparation. No idea what this means?

Lastly there is no evidence of the injectors being replaced, the vehicle has covered over 150k so i presume it didnt have the faulty batch installed?