[Hellz]

i dont have a answer for you, but maybe a little insight

not many cars ( if any) carry capacitors to store electricty in them.
so keeping the battery unplugged for 48 hours isnt going to accomplish anything more than if you unplugged for just a few minutes.

now i would agree to leave it unplugged for a short amount of time..( few minutes, not hours) as there is alot of devices and wires in a car that i woudl say need to get drained before running fresh current through.

devices that actually store information or what not will have thier own battery or power source, and wont be affected by the power loss/gain when you lpug/unplug the battery.

people can argue it all they want, and stick to what ever superstition they want, but it is all pretty much basic electricty, and computers.