Lyric discussion by afirefly 

Cover art for Keep the Car Running lyrics by Arcade Fire

I may be completely off base, but after reading over the lyrics a couple times I believe this is a song about giving up. Feeling inadequate against the challenges [of life] that the person must face. He's also feeling isolated -- they know my name because I told it to them, but they don't know where and they don't know when --in that people may know his surface, but nothing beyond that. They're not connected.

I think "I don’t know why but I know I can’t stay" and:

"If some night I don’t come home Please don’t think I’ve left you alone The same place animals go when they die"

...are him saying goodbye, he's gone.

A common method of committing suicide is with carbon monoxide that's emitted from all car exhausts. This is usually done by closing yourself and car inside your garage and allowing the engine to run. Eventually the level of carbon monoxide will rise enough to kill you. Hence -- keep the car running.