Real, real simple calc. Actually, someone's probably already done this before. Bart runs from the Brooklyn Bridge to the Statue of Liberty and back in .04 seconds. I own the first volume of the Teen Titans reboot, so I don't have any scans right now. I'll get 'em later if I feel like it
worries
Spoiler:
Here's the feat:
Spoiler:
1000 meters on this map is 64px, while the shortest distance Bart could have traveled (which he didn't take, as he stopped to get a pretzel, cheese and all) is 348.20970692960298px.
1000m/64px=x/348.20970692960298px
x=5440.7766707750465625m
5440.7766707750465625m(2)=10881.553341550093125m
10881.553341550093125m/.04s=272038.833538752328125m/s
or about Mach 800.
Bart obviously took his blessed time, .04s was according to Tim Drake's reaction time (considerable, but not perfect), yadda, yadda, yadda. TL;DR, mach 800 is a low-end. Nothing special for a speedster.

Spoiler:
Here's the feat:


Spoiler:

1000 meters on this map is 64px, while the shortest distance Bart could have traveled (which he didn't take, as he stopped to get a pretzel, cheese and all) is 348.20970692960298px.
1000m/64px=x/348.20970692960298px
x=5440.7766707750465625m
5440.7766707750465625m(2)=10881.553341550093125m
10881.553341550093125m/.04s=272038.833538752328125m/s
or about Mach 800.
Bart obviously took his blessed time, .04s was according to Tim Drake's reaction time (considerable, but not perfect), yadda, yadda, yadda. TL;DR, mach 800 is a low-end. Nothing special for a speedster.