The last time I was in GM's Hamtramck, Mich. plant it was at the invitation of an old classmate who was working as a manufacturing engineer there. This was during the 1980s when it was strictly a Cadillac production line, including the final assembly of the Allante, where the bodies were shipped by air from Italy.
Chevy recently sponsored tours of the Hamtramck plant for the press as part of the introduction of the Chevy Volt. It was interesting to see how the plant had changed since the 1980s. For those who haven't kept up with changes in automotive production techniques, assembly lines are now much more flexible.
For example, during our tour of the Hamtramck plant we saw not just Volts, but Caddies, Buicks, and several other makes all coming down the same line. Unlike the 1980s, AGVs are now commonplace. The only robotic elements I can remember seeing in the 1980s were robotic welding cells for unibodies and a cell that put windshields in their place. In particular, the windshield positioning Scara robot was new and my recollection was that GM was still working out its bugs.
The windshield robot sticks in my mind because I noticed the worker at that particular station reading a newspaper in between operations. I guess the automated process left him with a lot of free time in between transitioning the robot to do its thing. In contrast, this time around I didn't notice anybody at Hamtramck with free time on their hands.
Ergonomics have improved as well. There was a lot more manhandling of big subassemblies in the 1980s that is long gone on the Volt line. Our tour host provided an anecdote on this score: He could remember when assemblers mounted tires and wheels on cars by bouncing the thing up to meet the mounting studs on the axle, which was about chest high. Those sorts of gymnastics are a thing of a past as the axle now passes the mounting station at wheel height: no bouncing needed.