It is known that paying big bucks for a diesel to replace a petrol car will take a while to recoup the savings, but keep the right diesel motor long enough and there is no denying there are savings to be had. Yes they are not the same to drive as a petrol but it really does depend on your needs. Not sure how old the previously mentioned transporter was but I know most, especially early ones tend to be woefully underpowered and lets not forget how heavy they are. I have a petrol T25, it's consumption is one of the worst I have experienced, almost as bad as a 5L Mustang we used to have.

A lot of people don't actually know how to drive a diesel and often it's these sort of people that complain about poor MPG. A close friend spent years driving his like a petrol, redlining it to get power that didn't exist at the top. Poor MPG and often suffered engine problems due to the abuse.
The Audi posted by the OP hasn't got the greatest diesel in the world and for an estate will be quite underpowered, but I assure you I could get much better MPG from it than a petrol equivalent if driven correctly.
If I drive my 2009 Mazda 6 (2.2 MZR Diesel) like I stole it, I get MPG in the 30's, something the same powered petrol version only manages when driven carefully. On long runs I get mid 50's, late 40's with four people and camping gear on a trip all the way to the Swiss alps and back. This is impossible in the petrol, I tried.
All engines, petrol or diesel can return poor MPG, especially if the engine doesn't suit the car (too small for the weight it has to carry) or people expecting acceleration in the same manner as a similar sized petrol and therefore thrash it like a petrol.
As far as servicing goes, I think some manufacturers over service IMO and I'm sure it's just a money spinner. Buy an older diesel and you can often get away with murder and do very little to it.
Diesels are usually much stronger as they need cope with high compression, and more often than not munch more miles before packing in as a result.