I live in California and can attest to this as I have asked several different LAPD and LASD officers that I have seen around various different sections of the area I live in and they all have confirmed that their vehicles have changed from amber-blue to red-blue. They didn't list the reason since they didn't know, but I suspect that since the Arjents, valors, etc are red blue and amber lights, and most of the older slicktop marked supervisor vehicles and slicktop unmarked detective vehicles are red-blue instead of red-amber that they just wanted to have all their fleet vehicles match. But like I said its a suspicion of mine but I could be wrong.