Question: What is DriveShaft?
The term "DriveShaft" was first introduced in Episode 1x1, Pilot Part 1.
Answer: DriveShaft is the name of the band that Charlie was in. They had one hit song, "You All Everybody," and were popular for a short time. Charlie's brother, Liam, was in the band with him. Liam got into drugs and eventually Charlie did too. When Liam got clean he wanted nothing to do with the band, but Charlie wanted to start the band up again.
DriveShaft plays at the benefit concert at the museum in the flash-sideways (Ep: 6x17, The End).