LPG (Liquefied Petroleum Gas), which has a higher content of hydrogen than gasoline, has been attracting worldwide attention for its various advantages. These advantages include low emissions of greenhouse gases and, as a result, LPG has little influence, direct or indirect, on the ozone layer. The electronic feedback-mixing system of a conventional LPG engine, however, has certain disadvantages to a gasoline engine with respect to output, air to fuel ratio control, charging efficiency and fuel economy. For these reasons, the majority of current bi-fuel vehicles in Europe employ a LPI system that injects LPG in liquid state that attempts to make up for the shortcomings of the feedback mixing system.
The mono-fuel vehicle recently developed by HMC performs with the same output level, torque and fuel economy as conventional gasoline engines by employing the world's first liquid-state-injection system for exclusive use of LPG. This has improved the problems of the electronic feedback mixing system and bi-fuel LPI system. In particular, the improved fuel economy of the vehicle is expected to help cope with future regulations relating to environmental protection from exhaust fumes.