[upflying]

I will reserve judgment here since we are only hearing the OP's version of the events. Without the benefit of internal affairs investigations, judges, juries, attorney's, witness statements, video/audio evidence, denigrating cops is easy to do in any discussion forum. Reading between the lines here, I would reckon two groups of teens driving a Camaro and a Mustang on the freeway were probably engaged in doing something that is not being admitted to by the OP.
Threads like this do nothing to support the image of law enforcement. The LEO isn't here to defend themselves and the hatred gets erroneously and ignorantly perpetuated.
How is it that I have driven on California roads for 40 years and no LEO has ever done this to me?
I will say though that California LEO's specially assigned to traffic enforcement must drive marked (black and white) police cars. While plain wrapper or unmarked cars can make traffic stops, the officers cannot be assigned to the duties of traffic enforcement. Here is the law..

40800. (a) A traffic officer on duty for the exclusive or main
purpose of enforcing the provisions of Division 10 (commencing with
Section 20000) or 11 (commencing with Section 21000) shall wear a
full distinctive uniform, and if the officer while on duty uses a
motor vehicle, it must be painted a distinctive color specified by
the commissioner.