Is the Ford Crown Victoria really the most commonly used car by undercover policemen?

Is the Ford Crown Victoria really the most commonly used car by undercover policemen? - 1

Hell NO!
The Ford Crown Vic interceptor is a well known police vehicle.
No "Undercover" copper would use one
The Undercover car of choice is a nondescript <anything> that fits the area. Often chosen from the Impound lot.

"Undercover" means NOT being identified as a cop, blending into the neighbourhood. You don't need the power or Speed for Chases (except in TV & Movies).

Also, mentioning that the Crown Vic was discontinue in 2011 it has been replaced by the Ford Taurus (sixth generation)

Not any more. Ford stopped building Crown Vics several years ago, and MOST police departments have retired their big Ford sedans in favor of newer cars.

Nope, the police officers that I know who do surveillance or plain clothes work, use common cars that don't scream "I'm a cop". Minivans and very ubiquitous cars like the Camry are what they tend to use.