I have a few:
What if Toyota had bought Jeep when AMC went under instead of Chrysler?
What if Hummer hadn’t lost sales due to being politically incorrect in the early 2000s?
What if the Oldsmobile diesel engine was good?
What if the K-car hadn’t made FWD normal, and expected?
What if the “big three” were from different states instead of all based in MI?
This could be a fun thought exercise.