I would expect the guy to be acquitted.
First, if it's not illegal, it's legal, bad manners notwithstanding.
Generally speaking, generalized theft statutes don't fit very well with intangible property like electricity. I doubt the prosecutor is looking forward to proving how electric transmission works and what specific property was actually, beyond a reasonable doubt, taken. Maybe it was charged this way because a couple of cops sat around and tried to figure out a way to get this guy, rather than taking a reasoned approach to the matter, and the prosecuting attorney will amend or drop the charge, or maybe the Georgia statute works for something like this. My state has a specific statute for theft of utility services to make prosecuting it less problematic.
Second, with the exception of a few strict liability crimes, one not only must commit the proscribed act, but also simultaneously have the requisite mental state (mens rea) associated with the crime. People commonly use electric outlets in publicly owned places and I strongly doubt that they think of this as an illegal taking of property. I've never heard of anyone in my area being prosecuted for it. It seems unworkable to me to think that a little theft will be dealt with not at all, but a little bigger one will be prosecuted. There are actually some important constitutional principles involved with reasonable notice of what is illegal and what is not. If this outlet is located in an area where the public would not normally have access, then obviously this becomes more problematic for the defendant.
Indeed, many people do not perceive the taking of intangible property as even being wrong. While not a particularly close analogy, there is now a whole generation of people that will bitterly defend the "right" to download copyrighted material on the basis that they haven't really taken anything.
The easy and legal way to deal with jacknuts like this is to just pass an ordinance that you can't plug your leaf ( or volt or whatever ) into an outlet that is not your own or specifically provided for that purpose. That way it's clear what is illegal and you don't have to worry about busting kids for plugging in their Nintendo at the park.
As to the cop, his spelling skills are immaterial. I understand the car was unattended, unlocked, and on public property? Generally, police can do anything the public can do, and if a member of the public could have walked up to this car in a public place, opened the door, and rifled through the glovebox, I think it's a tough sell to say the cop couldn't do the same. Where's the expectation of privacy in an unlocked car on publicly accessible property? If it had been on private property, where the cop would be "breaking the close", then it could be looked at in a different way. His reason for doing it was certainly a lame pretext, but I don't think it matters.
