Felix Wankel was a great inventor, having invented the rotary engine with no university diploma on his resume, just experience from working in a book shop. In the 1960s, it seemed like the Wankel engine was going to be then next great innovation in car design. Even GM bought into the hype....
The engine ended up being too thirsty for the fuel-crisis '70s, and by the end of the decade only one carmaker stuck around with the rotary: Mazda. After earlier dreams of a full-rotary lineup, Mazda kept the engine going in its fantastic RX-line of sports cars, which ended up being the final cars to use rotaries.
It's because of this orphan status, and because of the legacy of cars like the double-rotor 1990s RX-7, the triple-rotor Cosmo, and the wailing, Le Mans-winning, quad-rotor 787b that the Wankel engine, and its creator have a quasi-cult following. Some call them rotards.
You could call Felix Wankel a bit cult-ish, too, but he was more interested in militarizing the Aryan race than restoring sports cars. Born in 1902 in the Baden state of Germany, Felix Wankel was an early supporter and member of the Nazi Party. He saw his first Nazi rally on a trip to Bavaria with his widowed mother in 1920, writes Marcus Popplow in Felix Wankel: more than an inventor's life. You can read much of the book right here on Google Books, if you speak German. A comprehensive summary of his Nazi career starts on page 36.
He was hardly 19 years old when he joined the 'German People's Protection and Defiance Federation' in 1922, the most active anti-Semitic group in Germany at the time, which is probably saying something. Only a year later he was a member of the official Nazi party, the NSDAP.
Throughout the 1920s, Wankel regularly traveled in public wearing a swastika, and when he posed for pictures, it was often with one on, writes Popplow.
Popplow also notes that Wankel often wrote anti-Semitic passages in his diary, though during interviews in the 1980s Wankel stated that these entries, along with anti-Semitic leaflets he distributed, were only youthful mistakes.
In 1926, Wankel met with his regional leader of the Nazis, Robert Wagner and was appointed to run Baden's Hitler Youth. Wankel, however, fell out with Wagner, as Wankel wanted the Nazi party to be more militaristic. Wankel was so displeased with Wagner's more political aspirations that he publicly accused Wagner of corruption in 1931.
Wagner stripped Wankel of his title and then kicked him out of the Nazi Party. The Badische city archive gives a quote from Wagner, describing how much he hated Wankel.
Wankel is a man of entirely one-sided intelligence, which produces only in the negative ... thereby poisonous ... acts.
Wankel didn't stop his accusations, and Wagner had him arrested in '33. Of course, this didn't stop Wankel, a charismatic speaker (as noted by the local Badische newspaper) with good connections thanks to his technical presentations to top-ranking Nazis. Hitler's economic adviser got Wankel out of jail and Wankel formed his own splinter Nazi party in Baden.
Wankel got himself a federally-appointed factory in Lindau in 1937, and though he was initially denied re-entry into the Nazi Party, Hitler's economic adviser intervened once more to make him an officer in the SS in 1940. In 1942, Wankel was kicked out by the Nazis once more, for unknown reasons. After the war, the French imprisoned him for his Nazi ties.
It's difficult to disassociate the man's Nazi side from his inventions, because his Nazi bent was particularly turned towards technology. Wankel even met with Himmler (you can see a photo of this meeting right here) and also Hitler to discuss the importance of technology and technical education. Wankel's best connection to the Nazi party came from Hitler's aforementioned economic adviser and industrialist Willhem Kepler. His first car, and his first rotary engines were built in the 1920s and 1930s.
Some argue that Wankel may be a brutally misunderstood character — that his Nazi ties were only to support his technical career, that he was making a deal with the devil, so to speak.
It does not appear that there is evidence to support this theory. I think you can gather that Wankel wasn't a casual member of the Nazi party. He was booted out once (if not twice) for being too radical. The guy was a Nazi.