I know of two guys, who were customers of mine, used it in the 50's in their "Rail" dragster. It was fun listening to them on how it was installed so it couldn't be seen.
The technique was used during World War II by Luftwaffe aircraft with the GM-1 system to boost the power output of aircraft engines. Originally meant to provide the Luftwaffe standard aircraft with superior high-altitude performance, technological considerations limited its use to extremely high altitudes. Accordingly, it was only used by specialized planes such as high-altitude reconnaissance aircraft, high-speed bombers, and high-altitude interceptor aircraft. It sometimes could be found on Luftwaffe aircraft also fitted with another engine-boost system, MW 50, a form of water injection for aviation engines that used methanol for its boost capabilities.
In a 1914 patent, American rocket pioneer Robert Goddard suggested nitrous oxide and gasoline as possible propellants for a liquid-fuelled rocket.[5] Nitrous oxide has been the oxidiser of choice in several hybrid rocket designs (using solid fuel with a liquid or gaseous oxidizer). The combination of nitrous oxide with hydroxyl-terminated polybutadiene fuel has been used by SpaceShipOne and others. It also is notably used in amateur and high power rocketry with various plastics as the fuel.
I was going to say the Luftwaffe, but Korrie beat me to it. Another example of aviation leading the way is the turbocharger.
I think the first to market kits for cars was 10,000 RPM. I know Ron Hammel the founder of the company passed away in 2012. They had the small ads in the back of the car magazines back in the day.
The use of nitrous oxide (N20) as a performance enhancement has been traced back to World War II, where it was employed first by the German Luftwaffe to give their fighter aircraft “emergency” boosts in both airspeed and altitude capabilities. The primary aircraft utizing nitrous oxide injection was the Messerschmitt BF-109 outfitted with the "GM-1" system. Nitrous was used by the Allies as well on various aircraft in response, notably on the American P40 and some British aircraft. However, with the advent of jet propulsion toward the end of WWII, and the resultant phasing out of piston-driven fighter aircraft, nitrous oxide R&D was shelved. There were sporadic attempts at using nitrous oxide in race cars over the next couple of decades, but for the most part it was a clandestine, closely-guarded secret, and not too many people were aware of its existence. NASCAR legend Smokey Yunick was rumored to have experimented with nitrous oxide in the 1950's, but not many other "known" racers even knew about it. Early attempts at using nitrous on racing engines led to some discoveries, both good and bad (the bad leading to some of the rumors and misinformation about nitrous use today). Around the 1970s, nitrous use started to pick up. Astute racers such as Mike Thermos, Dale Vaznaian and Marvin Miller saw the potential for nitrous use in race and street cars. Enthusiast publications of the day, (Hot Rod, Car Craft and Popular Hot Rodding to name a few), started running tech articles about the safe use of nitrous oxide, and interest started to take off. Savvy racers (drag and street racers alike) saw how easy it was to make "horsepower on demand". Perhaps the single greatest boost to the popularity of nitrous oxide was the advent of drag racing’s Pro Modified class. Early pioneers in Top Sportsman racing (the forerunner to Pro Mod) such as Charles Carpenter, Bill Kuhlmann and Rob Vandergriff captured the imagination of race fans with their impressive performances with stock-bodied cars. These early cars evolved into todays low 6-second "bottle rockets" seen at IHRA and NHRA events. Today, nitrous is used in a lot of applications, from Pro Mod racers to serious street cars. Other uses of nitrous include motorcycles, Powersports, and even RC applications!
Many do not realize that the Hemi head was a WWII aircraft engine head design by Chrysler. It came too late to make it into the field. I met one of the mechanics for the engine many years later when I flew into grass strip that still bears his name (Joe Hurdle) in the early 80s. http://www.airport-data.com/airport/4W7/. On the floor on his hanger was one of the v16 Hemis (2200 cid 2500 hp) https://www.allpar.com/mopar/hemi-aircraft.html. Joe has passed. Joe told me that when he passed, he made a deal that the engine was going to the Smithsonian.
