Was cleaning out my desk and came across an answer of sorts to this question I originally answered. At some point, I fought my way into the incredibly involved and arcane database of EPA emissions test results and found the attached data. Although I forget the exact search args I used, what you see is here is, IIRC, applicable to the Mk4 Jetta. I would have been searching for what applied to my 2003 Jetta. Anyway, there are three data sets
- Jetta TDI with manual tranny
- Jetta TDI with auto tranny
- Jetta gasser sister car (dunno whether manual or auto)
As expected, the diesel had better CO2 emissions, but worse NOx
http://sdean.net/cars/'03JettaGasVsD...ssions0001.jpg