yup the body sheet metal is pretty thin. The metal feels fairly sturdy to do the bends and what not. I think even some of the newer cars may skimp up to 24 guage. Typically i would except to see 20 to 22 gauge.
Older vehicles probably had thicker metal, however thats when big and heavy was the style...now car manufacturers want to make their cars as light as possible for fuel mileage and the such.
Nathyn