Just came back from a 800 mile trip to Greenville SC with my new Rav4 2017. Had to experiment with the cruise control. It now appears to me that what is meant by Radar Ready, is that it is tracking the car in front of you that is xx feet ahead of your car. If they slow down, your car brakes are automatically applied to keep a constant distance. Likewise if they speed up. And if you change lanes where there is an open road without a car immediately in front of you, your car will resume the max setting for the cruise control. I drove for an hour without touching the brake or accelerator, with the cruise control constantly adjusting my speed. Careful however, it does not anticipate a driver quickly changing lanes, or on ramp cars--that you will need to apply brakes.Curious about the cruise control "on" button. If you push the button in to activate cruise control on the 2017 Rav4H (and the message on the screen says, "Radar Ready") and you don't select a speed, does anything actually happen with the radar now that it's ready?