Leap over a tall building in a single bound
He leaps. At least, that was the cinematic explanation in
1978. I can't recall exactly how it was explained, except that it's not intuitive; he shouldn't be able to turn quite like he does, and he certainly should not be able to hover as he frequently did in Superfriends cartoons. But it has to do with Earth's yellow sun powering his strength; his body is unusually dense compared to Earthlings, which has something to do with deflecting bullets. Nonetheless, as I recall, his mode of propulsion was to simply leap with such strength as to defy gravity in such a manner. Strange, then, that he never left holes in the concrete like the
Power Puff Girls, whose Chemical X powers include simple defiance of gravity.
Or so says my two cents.
I didn't find a web page discussing Superman's propulsion directly, but that just means I haven't found it yet.
Remember:
Faster than a speeding bullet!
More powerful than a locomotive!
Able to leap tall buildings in a single bound!
Look, up in the sky ...!
(
Note: Bryan Singer's 2006-slated
Superman Returns, starring
Brandon Routh as Superman and
Kevin Spacey as Lex Luthor, begins filming in March.)