Reactivity Controlled Compression Ignition (RCCI) is a style of combustion that uses two different fuels and results in a super efficient engine. Thermal efficiencies as high as about 60% have been found in lab testing, which is remarkable for internal combustion engines.
Combustion relies on a low reactivity fuel (in this case gasoline, though ethanol and natural gas can also be used) in combination with a high reactivity fuel (in this case diesel fuel). The engine benefits from the individual advantages of each fuel, resulting in exceptional efficiency and significantly less harmful emissions. Check out the video for details about how it works!