I can do better - 4 door Suzuki SX4 gets well north of 30mpg in actual driving (a buddy with one just told me about getting 39mpg out of his), and an out-the-door MSRP under 17K. I'm actually looking at something like this as my next car. Except my current car is running great and I don't have a spare 17K laying around. ;-)
You're right though. Your numbers or mine - just goes to show the Volt makes no sense whatsoever from a practical standpoint.
If you overinflate your tires by about 30-35%, you can significantly improve mileage as you will reduce rolling resistance. Just don’t do it in the winter.