I picked up my 2013 Volt exactly 1 year ago in early september. The most I have seen in the morning is 87km (54 miles) of charge on the battery. The other day we went for a ride in the country. I turned on the ICE when we hit the highway, but I love switching it back to battery if there is a good downhill run so that I can add some charge. I soon had it back to the 87km I had when I left. I turned off onto a side road and found myself at the top of a steep hill. I put the Volt back on the battery and coasted and braked down this long, steep and winding road. When I finally got the bottom, the car showed 97km (62 miles) on the battery. It actually hit 97 well before the end of the descent and I concluded that perhaps it was designed to top out at that number for display purposes. I think I actually had more than 97 as I seemed to drive several km before it went down to 96. I eventually used that all up and came home on the ICE. I don't know if such charging can actually increase your battery storage capacity, but the next morning the car showed 91km of charge.