The electricity an device uses when not "on" is called "dark current". Many appliances (especially entertainment electronics) keep circuits running to monitor the appliances status. The transformer block chargers for cell phones and such use some electricity when they are plugged into the wall even if nothing is plugged into them. Computers may be configured to go into "sleep" mode where most of the system is powered off but the CPU still runs slowly keeping data in memory so it can be available quickly when there is mouse or keyboard input. None of these items individually use very much electricity but the cumulative effect of millions of these devices remaining plugged in adds up to a great deal of energy.
Cars also have dark current. Car sterios usually have non-volatile RAM rather than flash memory and require a trickle of power to keep its settings. Cars may only draw a few milliamps but extra electronics like alarm systems, On-Star, etc can draw more power possibly leading to dead batteries if the auto isn't driven often enough but batteries also self-discharge (especially old ones).
If it's unplugged? No....but I think you meant "left plugged in"...whereas the answer would be, yes - some electronics so.
sorry, my mistake. thanks :)
