My Adaptive Cruise Control has 4 distance settings and I use the 3rd, further than most people's following distance, and I've had stones kicked up by truck tires that hit my windscreen from that distance.
I do the same in my Subaru, even at the furthest, the safe distance is choose is no where near the 300feet(approximately 20 car lengths). It's closer to 8 car lengths.
Was curious so I just looked up my car's ACC numbers. Setting 3 is 1.8 seconds and setting 4 (the max) is 2.3 seconds, so about 220 feet at 65mph. As another poster said its pointless to be this far back because everyone else just overtakes you to fill the gap, so you're always braking and accelerating and averaging a smaller distance than in setting 3.
