Would that fit the OP though? Seems like Detroit would already be a mess at that point and we just create a nicer looking mess.
A certain downsizing is hard to avoid IMHO. Even if the big Three do Not Experience a massive Crisis, they Most probably Need fewer employees and will de-concentrate their production to a certain degree.
But if Detroit falls into an Apparent State of disrepair, it will Be hard, even with benefits, to lure Investors and well-qualified workers there. a wholesale Strategy against Crime is Another Point which has been mentioned.
Such policies would Be hard to apply, but others talked about butterflying WW2...
Generally, i think there is Little Possibiliy to avoid Car Culture. America pioneered it, but it is a global phenomenon, Even engulfing China now. To get rid of it, you have to either impoverish your citizens or to avoid the Invention of Mass-Produced Cars. Imagine- Even People who use busses, Rails etc Regularly might want to Own a Car.