On Sun, 12 Feb 2017 10:43:40 -0800 (PST), Christopher Tidy
wrote:

Hi folks,

Quick question. Many cars from the 1980s used to rust badly. Sometime in the 1990s, this changed - and quite suddenly. Does anyone know what specific changes were made to the paint composition and surface treatment? I can only find vague allusions in most articles.

Thanks,

Chris
Big thing was change to the surface preparation of the steel to
either electrostatic wet application or full body dip of a high
quality etching primer which I believe contains Zinc.
This was combined with the use of high strength steels and
"galvanized" steel in rust prone areas.