When I worked k9 most of my time I was plain clothes in an unmarked vehicle. I had a group of these bikers do something similar while they were next to me at a stop light. After leaving the stop light they all pulled into a local gas station and I discretely ran all of their tags and called for a marked unit. While waiting I started chatting them up about how nice their bikes were. They were very proud to tell me how they had just run from a LEO in a local city. When the uniformed guys showed up they didn't even pay them any mind until I ID'd myself and we started to get DL's. A few criminal citations later, I felt better about myself. FWIW, nobody expected a Geo Tracker to be a police vehicle.