Originally Posted by tjts1

For me, never having to deal with smog check or any sort of inspection in California was the main reason to switch from a gasser to a diesel. I had no desire to own a diesel until last year when smog check became an even bigger pain in the ass for old pre OBD2 cars. Going from 15c/mile to 9.7c/mile was just icing on the cake. I drive ~15k miles a year.

I doubt that. You would be spewing massive amounts of unburned HC if that were true.