A friend of mine owns one, the current A4 diesel.
As far as maintenance is concerned, it is nothing major compared to the segment. The engine is used even in VW, so spares are easy to get. The ride quality was better in A4 compared to BMW 3 series but Mercedes C Class is the clear winner. C class is good if you want premium feel & luxury, comfort; BMW 3 series is drivers car & less focussed on passengers, the tyre noise comes in cabin. Audi A4 sits between the C Class & 3 series.
However, it is now seen that lot of Audi components are making way in VW cars too. Eg. Toureg has elements taken out from Q5 or Passat has materials from A4. Go for Audi for brand, for value look for VW.
My friend in gym bought the 2012 C 250 CDI last month. He is getting 13 km/l. Maintenance is also quite low compared to the segment. This is one real rock dependable car in this segment. I would also suggest you to look at new BMW 3 series.
## The new Audi has lot of elements taken from existing Audi A4. The steering wheel though has changed now, with headlights. Price for diesel is some Rs.28.38 L, 2.0 TDI; Rs.38 L for 3.0l Quattro, the petrol TFSI is cheapest of the lot for around Rs.27.3 L, ex-Mumbai.