Hammerking was the establishing series of the Unlimited class, as we know them, the Ultra4 or 4400 race car. The defining characteristics of this class are the sturdy 4-wheel drive and unlimited builds. These cars come in all shapes and sizes, are capable of speeds over 100+ mph and contain gear ratios as low as 100 to 1 for technical rock crawling. Additional classes in Ultra 4 include the: Every Man’s Challenge which encompasses 4600 Stock, 4500 Modified and 4800 Legend’s cars. The fastest growing class is the 4900 UTV class and newest is the Electric Vehicle (EV) class. Motos and a Rock Bouncer’s Shootout are also held at KOH.

Ultra4 is a series drivers can showcase their unique capabilities, whether the driver has dreams of building a racecar in their garage during free time, or with factory-backed support. The series challenges drivers to compete in a wide variety of terrain from endurance desert racing, competition-style rock crawls, short course racing and more.

Currently Ultra4 has races in the US, Europe, Australia and New Zealand. These races take place on both public lands and on private property around the world.