After great advice from the forum I thought I would share what I think are some useful items. The three biggest things I would ask for when looking at an previous model year new Volt are: MSO, in-service date, and current mileage. These ensure that you get the tax credit and that you know exactly how much factory warranty you get.
The two biggest reasons to buy a Volt new are the tax credit and the warranty. As a recent buyer, I wanted to offer a small bit of advice in a compact space for others like me.
The MSO/MCO is a piece of paper from the factory that is a substitute for the title of a new car in dealer stock. When a title is issued, the dealer must send the MSO to the state, just like you would if you sold your car to someone else. If they don't have the MSO, the car has a title, and you can't get a tax credit.
Now for the warranty, According to the terms of the Chevy warranty, the mileage only starts at your purchase number if that mileage is below 1,000. If the car has more than 1000, you lose that mileage from the warranty.
More importantly, the date of the warranty starts from the "in-service date" of the vehicle. The dealer decides this, and for a car that was used as a demo or loaner it will be the date the dealer started using it as such. I read that on the Chevy warranty and asked my dealer to provide documentation of the in-service date.
For my new 2013, I lost 4 months and 1822 miles of warranty. Given the amount that I saved, it was completely worth it to me.
As an aside, many dealers offer something called "Warranty Forever" as a sales incentive. Ignore this. While it does seem worthwhile for a standard ICE vehicle, and most people who've used it seem satisfied, it is useless for Volt owners. It is a lifetime warranty on the drivetrain (although probably not the battery), as long as you follow the manufacturers maintenance schedule. I read the terms more carefully, and it says that, regardless of the oil life monitor or manufacturer instructions, you have to change the oil at least every 6 months or 6000 miles. That is ridiculous joke for a car that may have burned less than a gallon of fuel at that point..