I'll add a counter to the OP's experience. I was driving to SD and had the cruise set on 80. Going through Carlsbad, a CHP drove right past me at ~85-90. It didn't seem like he wasn't interested just because he had something more important to do.
2008 IB E92 M3| BBS | KW | Arkym | Platte Forme A.G. | Active Autowerke | K&N | Fabspeed | Dinan | Evolve-R