He worked and lived in Kansas City for many years as a consultant. After retiring, he moved to Butler, but realized that he was not ready to give up working. He opened a car dealership, which he named Max Motors after his son. He quickly gained widespread notice, due to his outrageous advertising practices and promotional stunts. In addition to the car dealership in Butler, he now owns a second dealership in Nevada, Missouri, and a towing company. He is the subject of the History Channel reality series, "God, Guns, and Automobiles". The show, which is in its first season, chronicles the day-to-day activities of Mark Muller, and his brother and business partner, Erick "Mancow" Muller, who is also a radio host. The brothers often butt heads regarding how to run the business.
