Action Comics #481 and 482, March and April 1978: the introduction of the Supermobile!
Why oh why does a man who can fly faster than the speed of light need a flying car with hands?
Because radiation from an exploding red sun struck Earth and re-activated the villainous android Amazo, which had been on display in the Justice League of America’s satellite headquarters. This same red sun radiation left Superman powerless.
Amazo managed to trap the majority of the JLA off Earth so they could not interfere with his nefarious plans. That left Superman as the only hero standing in its way.
Luckily, the Man of Steel had planned for such a contingency. He built the Supermobile, a vehicle constructed out of indestructible Supermanium, and designed to duplicate all his super powers.
Writer Cary Bates has stated that the Supermobile was not his idea; he had received an edict from on high to include it in a story.
DC Comics had entered a licensing agreement with a British company, Corgi Toys, which manufactured toy cars about the same size and scale as Matchbox cars. Corgi was releasing a line of Superman-themed vehicles in anticipation of Superman the Movie being released later that year. Among the vehicles in this line were a Metropolis Police Department police car, a Daily Planet newspaper delivery truck, and the Supermobile.
The original Corgi Supermobile was the same size as a Matchbox car, approximately 3 inches-long (top 2 photos). Corgi also released a larger version in 1/36th-scale (bottom 2 photos).
A few years later Kenner produced an armless-version of the Supermobile as part of their Super Powers line. That vehicle was large enough to hold a Super Powers Superman figure in the cockpit.
McFarlane Toys has released a new Supermobile based on the original design as part of the Super Powers revival line. The only major difference is the McFarlane version has red cockpit canopy.
Much like Spider-Man’s Spider-Mobile, the Supermobile was quickly abandoned. However, it was not forgotten. It has showed up, usually in the background, in a few cartoons and comic book stories over the years.