After 3.5k mi I have found the best technique for me. I am getting 76 - 79 mpg drafting semi's traveling at 62 mph. I have observed the Prius in hybrid mode, running the engine until my electric range increases by 1 mi, then it switches to ev. until the electric range falls by about 1 mile. It appears to be an automatic electric pulse and glide. I found that I am comfortable with the cruise following distance at 1 bar at 62 mph. Total trip distances are 360-400 miles straight, they include 1/2 straight flat freeway, and 1/2 mountain driving. Start with a full charge, end with no ev left. 76.1 mpg southbound, 79.1 northbound.
I've seen reports that this is how Hyundai/Kia hybrids, no plug, behave. They do use a larger battery than the Prius.
One bar of the DRCC is about 0.5 second following distance. I don't know why Toyota even offers the option.
That isn't even close to legal, let alone safe. The legal minimum in my state is written in terms of distance vs speed, but translates to 1.36 seconds.
I keep mine at 3 bars and often have to slow down for incoming or pile-up traffic. But even tho the car must build up speed again and probably cost me (a bit) 12.5 cents, I have this overwhelming sense of ultra safety. Traveling at 65mph now and Lifetimes gone from 124mpg to 121mpg. I’ll take that hit.
