This is how to get the JUST FLOOR IT Trophy (drive away without killing anybody in Chapter 17). Do yourselves a favor...if you want the trophy, don't do this on Crushing. It is infinitely harder. I was stubborn enough to push and find the split second window to do it on Crushing - proof it can be done. But really, just don't be stupid. Do it on an easier difficulty. Tips if you want to do this, you need to watch the heavy guy next to the jeep obviously, but wait until he hits his second post staring off the edge of the wall. When the guy in the background at the turret turns, that is the time to go. The guy patrolling on the ground in the red hat will walk away in his pattern while you watch the other two. Then just go...go go go. No breaks. No hand break. Just drift the jeep in the water (as if using the hand brake). If you lose control for a split second you are dead.