He is remembered mostly for his Opel RAK demonstrations of the world's first manned rocket-powered ground and air vehicles that earned him the nickname "Rocket Fritz" and which were also highly effective as publicity stunts for his family's automotive business.

[9][10] Opel-RAK was a series of rocket powered cars and planes commissioned by Fritz von Opel, in association with Max Valier co-founder of the "Verein für Raumschiffahrt", and Friedrich Wilhelm Sander.

[12] In the 1920s the experiments with rockets lead to speed records for automobiles, rail vehicles and the first manned rocket-powered flight on the 11 June 1928.

Also in 1928, one of his rocket-powered cars, the Opel RAK2, driven by von Opel himself at the AVUS speedway in Berlin, reached a record speed of 238 km/h, watched by 3000 spectators and world media, among them Fritz Lang, director of Metropolis and Woman in the Moon, world boxing champion Max Schmeling and many more sports and show business celebrities.

A stock corporation, registered on 3 December 1928 was founded as "Adam Opel AG " with a share capital of 60 million Reichsmark.

Opel, Sander, Valier and Hatry had engaged in a program that led directly to use of jet-assisted takeoff for heavily laden aircraft.

The German Reich was first to test the approach in August 1929 when a battery of solid rocket propellants supported a Junkers Ju-33 seaplane to get airborne.

The Opel RAK experiments excited also the interest of the German military, which provided funding for further development of rockets as a replacement for artillery.

Walter J. Boyne, director of the National Air and Space Museum in Washington, DC, concluded "Working together, von Opel, Valier, and Sander had thrown a big rock of publicity into the mill pond of science.

[22] He was present at the Secret Meeting of 20 February 1933 when German industrialists decided to support Adolf Hitler, but did not contribute personally to the donations.

[23] On 25 April 1940, Fritz von Opel was taken off the Italian liner Conte di Savoia by the British authorities at Gibraltar.

[26] The 1937 German film Weltraumschiff I startet –Eine technische Fantasie–, is a short movie made by Anton Kutter in 1937 about the fictitious launch of a space rocket that lands back on Earth after orbiting the Moon in an Apollo 8-style mission: In front of representatives of the press, the director of the Friedrichshafen airship yard announced the first manned rocket flight to the Moon.

Immediately before take-off, reporters interviewed the commander of the spaceship via video radio, which then flies over a kilometer-long ski jump into space and returns safely to Earth after orbiting the Moon.