I know just because when I bought it, that it had a few more options than my brothers and he had a black interior and was not as soft. Mine is Blueish/ash and it is so soft, even my color is iridium blue, Changes colours in day and sorta a silver at night. I was told napa is an upgrade on the S430 as you go to S500 you get more options as standard and the S600 even more . Not just the engine difference.