I never knew that. I don't run my car off it, but N-Propyl Nitrate is what fueled the Go-Kart that embarrased Tommy Ivo's twin engined Dragster in the 60s. Ivo then got beat by a VW beetle that was Thermolene powered. But they had jet engines. (really a Quickchange rear flipped backwards, with a nozzle that provided thrust, and the spinning turbine spun the axle.)
89 Octane, a tank of 93 every 3rd/4th tank (the engine's supposed to used it, anyhow).
Using a lower grade of fuel tends to make engines a littel sluggish, customers who drive our loaner cars with 93 compared to cheap stuff that they put in their car definately notice the difference.
Sometimes the oxygen sensors burn out quicker on cars that use less-than premium grade fuel, but the O2 sensors are kind of poor quality in our cars anyhow.