My otherwise flawless 2011 with 105,000 miles has exhibited this situation twice now. Normal cold weather battery range of 30-33 miles. The drive uses up the battery range, the engine comes on as normal but there's only 2-3 miles left in the trip so it runs at low rpm. I park outside in the 35 degree weather for an hour. Back in the car start it up and immediately have the "Reduced Propulsion " message with no check engine light. Start driving the engine revs up to what must be max rpm for about 2-3 minutes and of course acceleration is sluggish. After this high rev period the message goes away and normal ICE operation resumes. Yes I see another post describing this scenario with one case with a Volt still in warranty getting a battery replacement on GM. Are we seeing normal to be expected slight degradation of the battery which is triggering the programmed action? In other words normal per system expectations? My workaround may be to engage mountain mode 3-4 miles from destination to bump up state of charge. Or is the battery degradation which seems minimal a concern or cause?