You can get away though, if you are sneaky. I got the away from a 4 star chase earlier (for the achievement) on foot. Unless a cop can line of site you the radius thing wont recenter on you, so outrun the chopper, then get out of the car and start jumping fences and going around the backs of buildings and you'll get away.
The targeting thing is annoying though, it always wants to point at the old woman with her back to you, rather than the FBI special forces bloke with an Uzi firing it at your head.