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.