I am going to take a wild guess and figure that it would take a few years to account for the cost of the vehicle in gas savings.
Then there’s the question of how much profit is made for each Volt sold. I am confident that electric/hybrid vehicles are going to continue getting better, but when you consider the financial status of GM, and a lot of details about the Volt, I have a hard time buying into how great it is.
Many people did the calculations (including myself) and the result is that Volt will break even somewhere between 12-15 years and never.
The reason is that you have to pay about $15-20K extra up front. This money could be invested instead, and by the end of those 12-15 years you would end up with a tidy sum of $40K. So if you have $40K today what would you prefer: to buy a gas car and 15 years later have money to buy two new gas cars, or to buy one Volt and 15 years later have an old Volt and no money?
With a gas car you spend your fuel money as you go. You have money - you go on a road trip. You have no money - you stay at home. With Volt it's all prepaid. Doesn't matter if you have (or don't have) a job, if a family member is sick - you can't take that money out and use elsewhere; it's sunk into the car forever.
The "never" part comes from the fact that Volt's batteries are expected to last not more than 10 years. To replace batteries you need to spend untold tens of thousands of dollars, so for all practical purposes once the battery dies the car dies with it. If the break-even date comes after the car dies, it means that you never save any money on the purchase.
Also, Volt would be an easier proposition if it were to be a diamond ring, for example. You'd put it into a safe in a bank, and it would be secure there for generations. However a car is not stored in a safe. It is parked outside, and it moves among other cars, in all weather conditions, on all roads. A car takes damage over time; sometimes that damage is so bad that the car is scrapped. It makes no financial sense to spend a huge sum of money on a car unless you are rich and are comfortable with the idea that you can lose it all in a blink of an eye. You usually insure the car, of course, but the cost of insurance is also proportional to the value of the car. An insurance for a Volt can be very expensive, so you'll lose money one way or another.
All in all, Volt would be a good car to buy ... if only it costs far less than what they sell it for. Probably $20-25K today would be reasonable; that's the cost of many good new cars. Volt is pretty chilly in winter, as I read, but it would have advantages too, so it would all balance out. Asking for double the cost is just unreasonable; using taxpayers' money to lower that cost is unfair.