I just realized I haven't seen many (any?) stories at hybridcars.com re. hydraulic or the Flybrid system (flywheel) hybrids.

UPS was supposed to accept and test 7 hydraulic hybrids in 2009 - 2010. They are 3x as efficient as electric hybrids at energy regen and their storage units don't degrade. They're supposed to be ideal for stop and go with heavy loads -- just the thing for parcel delivery, waste disposal trucks, etc.

I think I read that Jaguar was going to come out w/a car w/the Flybrid system ~2014.