I love how so many people like to throw the awful "spark plug" out there, like it is some crutch to gasoline engines.
With the exception of Ford's Triton engines (2 valvers spit them out, 3 valvers seize them in, and now they added a whole extra set), spark plugs are a non-issue. They last a long, long time, are generally not terribly expensive, and on pretty much all modern 4 cylinder cars are painfully quick and easy to replace. You could put all four plugs in a Nissan QA 4 cylinder in less time than it takes to replace the fuel filter in any TDI, and it only needs that done once for every five times the TDI needs that fuel filter changed.
So please, 1970 called, they want their ideas on gasoline engine ignition maintenance back, OK?
The things that stack AGAINST the TDI, cost wise, are the high initial purchase price, the higher PM costs, and the higher likelihood of a costly repair. Granted, some of this is just because it is a Volkswagen, and not necessarily because it is a diesel. Like the three dead Delphi radios we had this month... they die in TDI Jettas just the same as they do in gasser Jettas. But the turbochargers, the DPFs, the pressure sensors, etc.? Now that's all TDI.
Our shop's loaner Kia Forte, which is a nicely optioned up EX model, cost a whopping NINE GRAND less than the CHEAPEST TDI available at the time. Three years later, NOTHING has broken on it, and its PM items consist of oil changes every 7500 miles, with bulk [cheap] 5w20, a genuine Hyundai/Kia oil filter for a whole $6, a genuine Hyundai/Kia air and cabin filters for about $20, and a few tire rotations... When the car hits 100,000 miles, we'll sell it and get another. Sure, its resale value isn't great, but when you DIDN'T spend it in the first place....
(BTW, I think the Forte is a nice car... for someone else, not for me. But I won't argue that it is not an outstanding value of a car, it most certainly is).