Yes, the principle is posible, it is a matter of finding a legit brand/honest maker, because the oxidation happens when metal, exposed to humidity... (in dry weather/climates like Arizona in US has no rust problems, indeed the US air force airplane cementery is located there, and planes from eons ago are there in good shape)...and dirt, yes, dirt, ...(that is why it is important to wash a car every now and then, have you guys noticed that an inmobilized vehicle rusts faster than a car used regularly?, because dirt has chemicals that added to water/humidity, decompose and attack metal.Water is a accelerator, disolves the chemicals in dirt and transports it into every corner, and the oxigen in water adds to this process.) ...attack metal, especially through a" wound" or chip in the paint, but electricity plays a roll, and particles have to be charged for the process to happen...(as everything is in this world, even us people are electrically charged)...and a system like this one, if well made, interferes with this process, hindering greatly, if not completely, with oxidation. It would be great to protect our investment Datsun cars against rusting away.
I'll keep looking.

Jaime

If Dr Karl says it doesn't work..it doesn't work.
See:

http://abc.net.au/science/k2/homework/carrust.htm

I dont get it.
I just read the Dr Karl article, and he says that you need a complete circuit to make cathodic protection work.
Dont you have a complete circuit anywhere in a negatively earthed car?
Isnt that why the tail lights etc etc, work?
All this stuff is earthed back to the body to complete the circuit.
I must be missing something.
Can anyone explain it to a simpleton like me?

im pretty sure in high school science we learnt about this, but i could be mixing up two methods (i havent read articles BTW), you need a sacraficial piece of metal for cathodic protection which will rust more readily than the car, it apparently works but you need no rust in protected metal, which pretty much rules all of us out!

pretty much all my rust was caused by clumped mud holding moisture to the metal and it wasnt a rally car when i got it, just a lady driven road car which i suspect never had a decent wash in its life, make sure you clean out the wheel arches and in the back corners under the car because a lot of crap builds up in there and rusts the boot floor and bottom of rear quarters, as for the sills i havent figured out why they rust so much, poor drainage maybe?