With World’s Finest 77 (July/Aug 55) Hamilton, Swan and Kaye birth the first of many, many versions of a tale. One of the most obvious notions, the two changing powers. Or gaining and losing powers, to be more accurate.
I’ve been skipping the splash pages since the covers began showing the story, but in this case it is also the only front view illustration of the Supermobile.
An evil scientist builds a ray that will remove Superman’s powers, and give them to the scientist. Batman steps in front of the ray at the crucial moment, and gains Superman’s range of abilities.
Superman gets a cool Supermobile to drive around in, but otherwise relies on his costume’s invulnerability, and faking out criminals.
Pretty straightforward, they are both glad to return to the status quo as the story ends.