It isn't always a given that an add-on engine modification has an equal chance of showing up on the assembly line. A close friend of mine spent at least 5 years developing a 2nd stage device that the factory injector is piggy-backed onto. His theory that increasing surface area contact of the fuel to air at the molecular level would improve both power and combustion efficiency was documented on two different gasoline engines. He got an appointment with Bosch in Germany, taking with him his recorded engine laboratory test data done under varied conditions of octane, temp, rpm, fuel to air proportion, valve timing, injector timing,etc. He was a perfectionist and left no stone unturned. He presented it to Bosch's engineers, found them to be keenly interested in his invention, and returned home to the U.S. with what appeared to him and his lawyer to be a promissory agreement, pending actual road driven digital data from a x-country trip in U.S. With that he called Bosch back, got another appointment to see them and returned back to Germany with his lawyer in tow and his x-country data co-signed by an internationally certified engineering test drive group. Unfortunately, he was never invited upstairs where the real decisions are made and returned home disgusted and empty-handed. His take on it was that they might be interested in buying his patent pending out-right for not much more than he had in monetary investment, which I recall was about $200,000 USD, not including his labor. As others have pointed out, vehicle mfg's are paying their own engineers to step around patent pendings, so why should they pay shade-tree inventors a percentage of their sales?