Fiat took over Chrysler for practically nothing from Cerberus after a HUGE loss for Cerberus. At that point, the restructuring had been mostly done. Fiat's strategy was to get a U.S. distribution channel for it's own product line among other things.
I wonder if Sergio Marchionne would do it again. Chrysler has cost billions to bring it back to life with new products draining resources from the Fiat parent endangering the very existence of the parent. In addition, the Fiat 500, the first line to be introduced into the U.S. market, has failed miserably.
I think even GM would say that the SAAB acquisition was a terrible mistake. It was DOA, just hadn't stopped breathing yet.
GM acquired a majority share of Adam Opel in 1929, and bought the rest of it in 1931. Things have changed a bit since then.
With all the negative history in acquiring a troubled auto company, I'm not sure that people would be rushing to the door to buy GM. The bigger the company, the higher the risk. Besides, what would be the motivation for a competitor to take on the giant? Why not just allow a major competitor to die? No one was interested in 2008/9.