Bates, Swan and Chiaramonte introduce the Supermobile in Action 481 (March 1978).
Superman uses a teleportation ray to get him and Professor Ivo away from Amazo, and to the Fortress of Solitude. Superman mentions Kandor to Ivo, and he disappears from the story for a while. Superman unleashes a creature from his Interplanetary Zoo to fight Amazo,and provide some interesting visuals.
Superman takes advantage of the diversion to get to the Supermobile, a weaponized vehicle designed to duplicate his powers.
Oh, also, Ivo and Superman have figured out that a wave a red sun energy passed the satellite, stealing Superman’s powers, but waking Amazo. Neither of them were aware of it when it happened.
The Justice League, watching this from their satellite, also recap this information, and Batman explains that the vehicle is made of Supermanium, a substance almost as strong as the hero.
The fight in the Supermobile is fun. Yes, this is clearly a toy tie-in, but it works well in the story.
The Supermobile proves enough of a problem for Amazo that he threatens to kill Superman’s friend, who all just happen to be neatly lined up, watching the fight.