(Arrow Dynamics had debuted the first modern inversion, the corkscrew, a year earlier at Knott's Berry Farm).

Since Schwarzkopf's retirement, Stengel has worked on most of the world's record-breaking roller coasters, including Son of Beast, Millennium Force, Superman The Ride, Top Thrill Dragster, Kingda Ka, Dollywood's Mystery Mine, El Toro, Maverick and Olympia Looping, the world's largest portable roller coaster, among many others.

Seventy-two percent of the attractions on the 2004 Amusement Today Golden Ticket Awards list of the world's top fifty steel roller coasters were designed by Stengel Engineering.

Stengel received an honorary doctorate from Gothenburg University in 2005 for "inexhaustible creativity in linking physics and design to the experience of the body in roller coasters and other rides,".

[1] In 2002, he designed the "Stengel Dive," the roller coaster element that bears his name, for Goliath at Walibi Holland, Netherlands.