I guess I'll post this in general because I'm not convinced it is a "problem"...
Today I asked my 3 teen kids how they liked the Volt compared to the Challenger SRT that I traded and my boy says, "drift into the driveway and I'll give it respect".
So I figured just after I turned into my driveway I'd stab the throttle to at least give them a little scratch. I stabbed the throttle to the floor and released it immediately and it did exactly what I wanted: tires screeched and it lunged forward BUT: it continued to accelerate for about a half second after my foot was completely off the accelerator which also resulted in a longer screech than I was expecting.
Is this a known "phenomenon" in the Volt? I was thinking maybe the motor controller takes a half second to disengage or that maybe it doesn't cut power instantly to prevent shock on the drivetrain? The end result is basically a non-issue I guess: I was just used to ICE being more instant on the release. It was strange feeling the accelerator pedal in the full up position but the car still accelerating hard for about a half second. Also seems strange that the power came ON immediately as soon as I stabbed it but took a half second to "roll OFF".