Since that is a Zenki 180sx, if it is an OEM color it would be #KG1 Platinum Blue Metallic. Often times when that color is sun exposed it loses its blueish tint and becomes more silver. Paint looks to be in good condition however so it might just be a repaint of another color.
Here is #KG1 with some sun exposure:
Late model Kouki 180sx received an OEM silver color #KL0.