Pretty sure that is an odd-ball off shoot of a rental kart race.
Every time I find a link for rules, the page is gone.
Have heard rumors about them actually having letting real karts on the track, but not seen anything remotely that is hard evidence.
A word about the main track, and it's $50k rental fee.
They also requires racers to sign an agreement to pay for repair costs if they run off course, and hit something like a barrier,
and to pay a very steep 'environmental' fee if they blow an engine, or trans, and drop oil on their precious track.
Add to that the fact that is getting bumpy as hell due to the Texas clay moving around under it.
Just look at last years F1 race where the cars were getting air born at the entry into turn one.
Don't think I would run a kart there...