You might want to check that out. I do believe they also had the NX2000 in a 'Super White'. The all white NX's with matching door and bumper trim is much whiter than the '91 NX2000 with the grey door and bumper trim.
I could be absolutely wrong on this but I do think it was Vail White on your NX, but Super White on the '92-'93 NX's.
I have a 92 white nx and my door molding is actually grey instead of matching white like the 91, so maybe the 93 came with the all white nx....i dont know for sure. I know Marc the moderator has an all white nx and its a 93, i was actually looking at that one before i bought mine.....but the price i got for mine and the low 63k mielage was too good to pass up.