Probably not.If you live, say, at the top of Mt. Washington, start off to work with an 80% SOC, will the car allow you to brake-generate the batteries up to 100%?
I would assume that once the 80% SOC is reached, as you continue to coast downhill, the Volt's battery management software will probably stop the regenerative charging.
With the Volt, battery management is everything. Keeping the battery within the proper SOC will be crucial for maximum battery life.
This is just my opinion, not speaking from any experience.