non-reaffirm and auto has huge repairs

[joh]

What if a non-reaffirm auto needs a new engine or trans. Can you let it
go back not running ? How about if it broke down in another state?

[Chowder]

Much will depend on who the creditor is.

Typically surrendered vehicles have some amount of deficiency which is forgiven in the BK. What you are describing would not be a typical amount.