[tjts1]

In an interview with Fox Car Report Live, vehicle line directory Tony Posawatz sheds some light on the topic, saying that the Volt's sustained mileage will be "better than any conventional car, and we're trying to figure out how close, or if it will actually be better than any hybrids."

To put that figure into perspective, we'd imagine that means the Volt would fall somewhere between the 32 mpg rating of the Toyota Yaris and the 50 mpg rating of the Toyota Prius when running under charge-sustaining mode with an otherwise depleted battery pack.

Posawatz: Volt range-extended mileage to be "better than any conventional car." But what about hybrids? — Autoblog
The series hybrid fails again.