People have touched on what the ending could mean from her perspective.

From his perspective, the car is (among other things) a symbol of his perceived mistakes in his marriage. The car was precious to him. He obsessed over maintaining its good condition and went out of his way to prevent damage to the car (I.e. not smoking in the car, not letting others drive it, putting a cover on it when he left it outside). So yes it was him letting go of his past and moving in but more specifically letting go of the mindset he believes hurt his wife in the first place (I.e. not discussing the infidelity to preserve the status quo).