CNET runs a pictorial retrospective of GM cars (photos copyright GM). Here's some "firsts":

1927 - the first production vehicle created by a professional designer
1937 - the first concept car
1940 - the first mass production automatic transmission
1954 - a fiberglass body

1956 - a rear-mounted television camera;
1960 - Chevrolet Corvair, "unsafe at any speed";