The change to low sulfur diesel added steps to the refining process, and drove the cost of diesel up above gasoline. One of my boys bought a new VW with their TDI engine and he likes it, getting a best of 44mpg in his 25mile commute so far, still getting broken in. As has been said, the computer controls make them quieter and eliminate the sooty exhaust if pressed beyond their power limit at any given rpm.