For what it's worth, I have. I've noticed a bit of "schizophrenic" behavior on the energy graph during longer trips. Take a look at this video:
Start watching the energy meter at 0:20. Also note that despite me driving at 75 mph, the "since last charge" doesn't change from 103.3 miles. In fact, it didn't change for well over 15 minutes, then started jumping by a few minutes until it (mostly) caught up, although it still lost some mileage.
When it does this, responsiveness would go away.
(Video taken by my wife, in car with me. Sorry for the shakiness, she's balancing the phone on the steering wheel.)