It amazes me that, even after the science behind why it doesn't work (i.e. air is a poor electrolyte, that it works best when the car is immersed in salt water, but it only works well locally around the patches, which are meant to corrode away before the steel does) is pointed out, there are still people in 4WD forums who insist it works.
If you want to protect your car with a sacrificial anode, just galvanize/zinc spray it. Before you paint it. Modern cars are already negative earth. And sacrificial protection (like ERP and galvanizing) only works over small distances. It works better than alternatives (i.e. tin isn't sacrificial, so, if you scratch through the tin to the iron/steel of a tin can, it'll rust out the iron/steel immediately, no matter how narrow the crack), but it still needs to be a near-constant covering (I was always told only a couple of millimetres gap - as in, a narrow scratch in galvanizing won't cause the steel underneath to corrode immediately). Certainly, sticking 4-10 little dots around your car isn't enough.
