AUDI A6 2.5 TDI or VOLVO V70 D5

Hello municipality I am looking for your advice. At the moment I drive an A4 Avant 2.0 petrol engine and would like to enlarge. I would like the A6 Avant 2.5 diesel engine (from 2004 onwards), which one reads about the qualities and the maintenance costs of the engine does not sound so intoxicating. An alternative would be for me the Volvo V70 D5 also from 2004 onwards. Did someone ever have the possibility of a direct comparison ? Unfortunately both have not driven yet. Of the power of the engine are both equally think the equipment is better at the Audi In advance Thanks for the answers Patrick