I believe the first of the CV8Zs were sold from July 05 on....the one you are looking at might have been one of the first built (and complianced prior)
You should probably check the following features on the car to confirm:
- Sunroof
- Black bonnet nostrils
- Dark tinted tail lights
- Chrome version of the standard VZ Alloys with "CV8Z" embossed in one spoke
- White stitching on steering wheel, gear knob etc
- Interior rear view mirror is the el-cheapo type with a tilt feature (rather than the electrochromatic version that has a light sensor built in)
- No Alloy Pedal for footrest (only for other pedals)
I would say that would be a good point to start! Otherwise, ring Holden and ask them to confirm for you by giving them the VIN number....