Can a Cop Really Commandeer My Car?

I saw a scene in a movie on TV, recently, where Martin Lawrence flashes his badge at a black woman in a four-door Chrysler and demands she turn over use of the car to him and his buddy.  The badge is not a police shield, but that of a security guard, because that is what Mr. Lawrence plays in this movie, and the woman does not give up her vehicle.  She drives the two men, calmly and at legal speed, to where they want to go. 

"All you had to do was ask nicely," said the woman.
"Yes Ma'am," said the two sheepish crimefighters.

These guys weren't real cops, but you've all seen TV shows and movies where this commandeering happens.  Is it for real?