Fact: Honda was the only car manufacturer, in the 70s, to produce a car that met the "1970 US Clean Air Act" without using a catalytic converter.
Details: In 1970, a bill was passed, which required all cars to reduce their emissions to 10% by 1975. This was a difficult task for all of the car manufactures, who wanted to continue selling automobiles in America. So, most of the car companies used catalytic converters in response to the act; the converters were used to lower carbon monoxide, hydrocarbons, and nitrogen oxides from our vehicles emissions. The downside to the catalytic converters were that they did not respond well to leaded fuel, and fuel efficiency was harder to obtain. With that in mind Honda produced the only engine, during that time, that did not rely on a catalytic converter. They called it the "compound vortex controlled combustion" engine, which Honda used to develop the 1975 Honda Civic (for the US). This was one of the first contributing factors to Honda's wonderful success, and reputation in the American automobile market.