In the random idea department, I'd submit that hot dog cart to MTV's Pimp My Ride just to see if you get lucky!
Ohhhh if I had more time I'd be doing some major photoshopping.
Consider doing something funky with the cart - here's some random images:
add a canopy (good on a rainy day) - maybe like a beach cabana
paint firestreaks on it like you would a 67 mustang (muscle car)
add a some funky wheels to it
add some really cool-looking mufflers/exhaust pipes on the bottom sticking out the side
go with a circus theme (circus tent/bright circus colors)
go with a ballpark theme - add penants and team logos
you get the picture - do something wild.
Hollywood Dogs
Dogs on the Run
Moon Dogs
Dog Weiners (ok, skip this one
Reservoir Dogs
Circus Dogs
Grand Slam Dogs
Boon
Doggle
Dogs 101 (only need 5 ingredients for over 100 combinations)
just something catchy....
Good luck!
And remember - location, location, location.