old man neri

I get my honda oil sprayed every year. I suppose you could do that to a porsche. Although, I wouldn't do it myself.

CN

No need for an electrolyte if all metal parts on the car are grounded and so is the magnesium anode!! The metal is the conductor.

Tom Tweed

My understanding is that for galvanic corrosion to occur, three conditions must be present:
1. Two dissimilar metals
2. An electrolyte (water with any type of salt or salts dissolved in it)
3. A metal (conducting) path between the dissimilar metals.

I have heard of cathodic protection for cars, but they are usually more complicated and expensive, involving an impressed current. From one such manufacturer:

"Cathodic protection, used in its classical form, is not effective in atmospheric conditions because it relies upon an electrolyte (usually water) to surround the anode and the entire metal being protected. The electrolyte then bridges the gap between the anode and metal being protected enabling the required current to flow between the two and interfere with the rusting process.

This means "classical cathodic protection" would only be effective on a vehicle if it was either submerged in water or completely covered with some other conductive coating (electrolyte).

RustStop® RS-4 electronic rust protection uses an adapted version of cathodic protection enabling rust protection in atmospheric conditions. This technology makes use of a clever combination of both sacrificial anode and impressed current technologies. Instead of relying on the electrolyte (water) to surround the anodes and vehicle, a current is impressed onto the vehicle forcing the electrons to flow though the metal and towards strategically placed positively charge anodes. The anodes corrode (sacrifice) and the corrosion process is interfered with."

Some other web references:
http://www.chem1.com/acad/webtext/elchem/ec7.html
http://www.corrosion-doctors.org/Car/carCP.htm
http://en.wikipedia.org/wiki/Galvanic_corrosion

It has been my experience that keeping a car clean and dry, as well as preserving the integrity of all the coatings used in its production, is adequate to insure it's survival.
TT