Are you absolutely sure you were in HV? Did the small HV icon appear on the console? As others have pointed out, if you take a break you have to remember to push HV again. Your experience is much different than mine, which is in line with what others have reported. I might lose a mile or two in a 50-mile highway leg, but that's much different than what you report. One thing you might try is observing the behavior of HV-Charge ... not suggesting that you want to use it on a regular basis, but knowing that it works as it should is another data point.