sinnerman gig

how the FUCK do you beat the "sinnerman" quest?? its the one where the bill jablonsky character wants you to kill some dude, but first you have to chase down the car carrying him. anytime i get more than 70 meters away from the car, he ends the quest saying "they got away"—like, buddy, I CAN STILL SEE THE CAR ON THE ROAD IN FRONT OF ME? WHAT DO U MEAN THEY GOT AWAY?? ive done it like 20 times and i cant beat it, especially with the way the other cars are literally lined up on each street an coded to get in your way the whole time. first playthrough i just let it go, but i really wanted to get it this time...