I can't help directly, but I can give you some information that may help.

We have this rack. We found (from talking to other people at the bike trails we go to) that the racks that go into 2" receivers are much more stable and have less "wobble" than the 1 1/4" ones. We had it installed on a Drawtite hitch that we put in ourselves that we got from Amazon for about $120. We recently had to have a new hitch installed on our CR-V for a road trip and Amazon could not get the hitch to us in time so we had to go to U-haul to have it installed. Prices were completable and the installation fee was only $50. I believe that the fee for the Volt would be closer to $80 because the exhaust needs to be moved in order to attach the hitch to the frame. You can go through the process of scheduling an appointment with U-haul to see the costs. You just want to make sure that they have the correct size (2" vs 1 1/4") receiver before scheduling.

I bought this one https://www.amazon.com/gp/aw/d/B0792V7HB5