You should make the edges of the lightbar in the back windows red and blue (or the same color as the other variations) so it looks better and makes more sense running them slicktop. Have at least some color flashing towards the back rather than just amber.
Hey just so you know, CHP do have slicktop tahoes and are i think more common to see than the normal tahoes. CHP also still use the slicktop, and marked rotator 2010 dodge chargers, however the rotators have been almost wiped out. The slicktops are still in use but are usually for show or higher ups in the department. The 2013 Tahoes are also used for patrol but like the 2010 dodge chargers they are most likely going to be driven by higher ups.