Downhill Extended Range Mode - Why?
I own a 2013 Volt for one week now and I have noticed some indications on the energy status display which I can not explain.
I live on a mountain and on my daily commute to work it goes downhill for the first 9 miles. I leave home with a fully charged battery in Normal drive mode and the gas engine is off as you would expect. On the way down the hill I use LOW gear and the system is in REGEN most of the time. However - the MILE indication is that I am driving in Extended Range mode, with a full blue circle and increasing number of blue gas miles being driven. Electric miles driven stays at 0.0. At the same time the available EV miles increase from originally 41 to 60, which is maximum on the display. I fully understand this part because of the REGEN mode. The gas engine is definitely NOT running and the used gas indicator displays 0.00 gal during the whole trip. Today I switched from LOW to D after 12.2 miles and at that time the indication started showing EV miles being driven. At the end of the 22.2 Miles trip to work the indication showed 12.2 gas miles, 10.0 EV miles, total miles 22.2 and 0.00gal of gas used. The available EV range at my destination still showed 55miles, which is way optimistic but explainable with the energy use during the first 22 miles.
The MPG indicator showed 250+MPG the whole time.
On the way back home the system is in EV mode from the get go until about a mile before I reach home. Then the High Voltage battery is depleted and the Range extender comes on. The final indication was total 45 miles driven, 32 EV miles driven and 0.03 gal of gas used (for the last mile).
Does anybody has an explanation why the system shows Extended Range mode during the downhill with the gas engine being off?