This weekend was my first opportunity to find out what actually happens over an extended distance over a variety of roads. 60 miles of driving with only a single charge, the first 9 of which were at 70 mph. That meant using the HV/EV toggle button to preserve EV capacity for use later. After that initial highway drive, it slowed to 55 mph, then 50, then a very long stretch at 30. That's when my curiosity peaked. Would the system automatically take full advantage of the EV capacity available, even though I was still in HV mode? Turns out, it does... which is a wise design approach, since STEALTH mode is the most efficient use of overall resources. In other words, you can drive and drive and drive in the Eco-Meter's green zone with a seemingly endless supply of electricity, quite unlike the usual distance limitation of the regular model Prius. .