Almost forgot about these. I passed a fleet of manufacturer-plated Colorados and Canyons on my way back from Chicago, including several pre-production versions of the ZR2. All vehicles had no badging except for the Bowtie or GMC logo on the front, and they had extra antennas on the roof and equipment in the cabin. I passed several groups of two or three of these trucks, but only got a couple shitty pictures because I was looking at the road, not the camera.

One of the new ZR2s from the rear with a Canyon in front of it.
A white Colorado ZR2 with black Canyons fore and aft.
Best I could do for a front shot of the ZR2.
A black and a white ZR2 in my rear view mirror.