Possibly unheard of electrical issue on 355?

Interesting. How exactly did you establish that there is 1v flowing through the body with nothing on?

 

With a charged battery disconnect the battery negative cable and jump it with an amp meter. See how many miliamps with nothing on and the car closed up.

 

There are some weird things about the 355. For example, when I was changing the headers on my car, with the battery switch turned off, if the cage around the bulb of my drop light touched the frame the doors would lock. Remove the drop light and they would unlock. I thought maybe the cage was grounded but when I checked it was completely electrically isolated from all 3 wires in the cord. Go figure.

 

You can predictably use an ammeter at the battery to estimate a battery drain in milliamps". Then you pull Fuses to find the offending circuit and narrow down the culprit from there.

 

As previously asked, where/how are you measuring this voltage?

Batteries don't like being flattened. I wouldn't have any confidence in a modern battery being flattened completely. I would suggest replacing it.

If you do have an ammeter hooked up in line with battery, I don't think I would turn on the ignition or attempt to start the car. The current draw may exceed the limit of the ammeter. Common multimeters usually only go to 10amps. A clamp type ammeter may be better for doing these tests.

 

Since it is so hard to access the battery on the 355, perhaps you could provide us with more details, and we can come up with some solutions which won't involve pulling the wheel and wheel well liner off the car.