My brother"s summer car is Jetta TDI station wagon. It is about 10 years old and it has served them well. He says it is a superb long distance high speed cruiser that they especially enjoy on their trips to visit their daughter in Arizona.
However he is not sure he will get another TDI when he needs to replace this Jetta. While it gets incredible fuel mileage, oil changes and the rest of the recommended servicing is substantially more than it would be for a gas engined vehicle. They don"t use it much if at all in the winter, because getting in and out of their place with much snow at all requires 4WD. So the potential winter diesel starting problems are a non-issue for them. But the price of diesel sure is--it is usually a bit higher than the highest priced gasoline, at least around here. My brother wonders if he could do better on a cost per mile with a gasoline-direct injection powered small car.
My brother just replaced his old winter car, a Suzuki 4wd with a new Subaru, but I have not seen it yet. They have had good luck with Subarus in the past.
VW has been making TDI type diesels a long time. However without researching the engine in the new vehicles, I would be hesitant to say it is proven. It might be substantially different than last year"s model. Manufacturers sometimes do that. On the other hand, I don"t know anything about the Cruz diesel--it might be great. But GM sometimes has put out products that probably should have been tested a couple of years more before they went into production. I would be very leery of a brand new diesel that the service departments of the dealers have no experience with. I remember the Vega and the various 350 diesels. Not the best record...and I pay attention to such things.
I would suggest driving both diesels and also trying some of the new gas-direct injection powered cars that have come out the last couple of years. If cost per mile is your main concern, you might be surprised at how well the GDI cars come out. But you are the ones who have to make the decision. Good luck!