The car itself is about the same size as a Cruze. Maybe a little smaller. The Cruze doesn't have the battery hump in the middle so it has a bit more room inside. Also the Cruze has an actual trunk. The Volt has cargo space in back with a cover, but doesn't have a separate trunk.
And something I might do with a bit of the refund is to put in a 240 volt charger in the garage - it'll cut the recharge time down to 3 to 4 hours and is supposed to be more energy efficient.