EPA gasoline permeability regulations and Ford gas tank design

Regulatory cascade case. Lead-coated steel ("terne") tanks replaced by plastic for lead-elimination reasons; EPA permeability limits then force a seven-layer composite. Tom's student at Ford worked the paint line during this transition.

Originally General Motors and Ford used to use lead-coated steel to make gas tanks. Not zinc-coated — zinc-coated steel will be corroded by some of the things in a gas tank, but lead has excellent corrosion resistance. They would use what's called terne, T-E-R-N-E, terne-coated steel, which is lead-coated steel. Then when they wanted to get lead out of the environment, they said, well, we'll just use plastic. So they started making plastic gas tanks. The designers thought this was fantastic — the plastic could be molded; the steel had to be stamped and formed, and you couldn't make it into the odd shapes that would fit into the little cubbies around the axle. With plastic you get more volume because you could mold this tank.