Don't speak ill of the [dead] TDI here! There are many loyal followers.
I wouldn't hold up a Jetta as a better vehicle over a Sonata, though. An MK7 Golf? Sure. Great chassis.
Like nick, I also look at total cost of ownership, and the TDI is hard to justify. If there was no price premium to buy one, I'd have bought one a while ago, but the premium, like a hybrid, takes many, many miles to make up.
I also keep my cars a long time and don't put value in claims for a supposedly lower depreciation with a TDI. I get rid of a car when its dead, or near dead to me. Depreciation is hard to account for at that state.
Take that 2015 TDI engine and put it in my 2016 TSI GSW for the same price, and yes, I'll be a happy TDI fan. Take away the MIBII and make me only have the Vtex seats, and no thanks, I'll stick to my TSI.