My son started racing quarter midgets at age 7. At age 11, we went to 600 Mini Sprints this year and he has already won an ASCS 2 race as well as races on our home track and is running 2nd in points.

The quarter midget deal helped him learn how to drive a car (smooth throttle, momentum, traffic, etc.) and helped me understand a little better how to set the open wheel cars up. A lot of the QM stuff translates to the 600 Minis.

Good luck.