Diesels still don't really save you money, but people still buy them. I think the reason to buy one is that you can still have a nice car AND not spend too much on fuel. If spending less money was paramount, as I've said before, there is only one model on the VW dealer showroom floor right now that can be labeled an excellent value, and it has spark plugs.
And the reason is simple: due to the expensive emissions compliance equipment, Volkswagen (and others) will only sell diesels linked to the higher trim level vehicles. So you are forced into spending [often signifigantly] more money. The Audi brand of course doesn't really have that problem, since EVERYTHING they sell here is pretty tarted up. And to that end, much of the Volkswagen brand's lineup is, too. We don't get an entry-level Golf here, let alone a Polo, or anything below that.
So if you were going to spend ~$25k on a car anyways, and the diesel was a little bit more AND you drove enough to justify that extra expense AND the driveability of the diesel engine in question was indeed superior as they often are, then certainly the car is right for you.
Just to give some food for thought regarding the Audi A6 (which I drool over like a dog with bacon):
There are 3 trim levels, Premium, Premium Plus, and Prestige. The Premium starts at $43,100, and is only available with a 2.0L gas engine. Premium Plus is available with 3 engines, the 2.0L for $47,400, the 3.0L (gas) for $55,100, and the TDI for $57,500. So you see, right off the bat, if you want a diesel, you'll spend a whopping $10,100 more to get one. However, it really in this case, since it IS a 6 cylinder, and it IS only available on the higher trim level cars, it really should be compared to the Premium Plus 3.0L, in which case it is only $2400 more. That, to me, is not bad at all. So if you were going to spend the coin to get into the higher trim A6 anyways, sure, you'd be stupid not to go for the TDI. Not only is $2400 a reasonable figure to recoup on fuel costs alone, but that value will probably stay with the car easily for many years to come, maybe even more since the gas version will probably depreciate faster. BUT.... you'll never recoup $10,100 that you could have saved had you just gone with the 4 cylinder Premium. And we won't even go into the Prestige pricing.... but rest assured, the most expensive version there also has no spark plugs. No more V8s are available for us.