According to the site, 1,236 Volt owners -- a 5% sample of the Volts now in traffic -- have volunteered to have their real-time statistics posted on VoltStats.net. There is a treasure trove of information that it far too much to describe in detail in this article. You are highly recommended to go there and slice and dice the data yourself, sorting by columns, and so on.
Most relevant here is the fact that several Volts tracked by the site have gone over 40,000 miles. If you extrapolate, you can estimate that there are another 20 times that number of Volts in total that have gone similar distances, with the possibility of a few outliers who have traveled even farther.
The Volt's Fuel Economy
It is important here to refresh everyone's memory as to how the Chevrolet Volt works. It's actually a bit more complicated than I have space to illustrate here, but the simplest way to describe the Volt is as follows:
The Chevrolet Volt is a powerful electric car, which can travel on average 38 miles until the battery has reached a certain low level. At that point, when the battery is, say, 20% from the bottom, a fairly regular 1.4-liter gasoline engine kicks in to keep the battery level from falling any further. This means that the powerful electric motor can continue to drive the car for as long as you have gasoline in the tank, which is nine gallons in the Volt.
When the gasoline engine kicks in, it will drink from the nine-gallon tank to the tune of 38 miles per gallon on average. That basically means you can go 342 miles after the 38 "all-electric" miles are depleted, for a total range of 380 miles. As with all cars, your mileage will vary, but that's the average. In other words, the Volt will take you on that cross-country road trip no differently than any other purely gasoline car.
What does this mean for the average person's fuel economy in a Volt? There is no easy typical scenario here, just a strict mathematical average. Different driving patterns mean that your miles per gallon will vary from over 2,500 MPG, which many people are achieving, all the way down to a theoretical minimum of 38 MPG. The highest Volt MPG that has been measured to date is 6,200 MPG.