i raced micro sprints for a bit (dirt), lots of fun, decent racing for an oval..... if you have multiple tracks in the area it makes it more fun, but its pretty expensive... Its basically a mini sprint car either powered by a 125cc two stroke, 250cc two stroke, or 600cc bike motor... the 600's are fast as hell, just as quick as a modified dirt track car (v8 powered big ass cars) because they are so light with a relatively powerful motor.
id love to try racing a shifter cart or something on asphalt too, but if dirts all you got then try it, its a fun way to get into wheel to wheel racing, learn how to set up the car, work on the motors etc etc on a smaller scale then say an SCCA car or something