Abstract: Homogeneous Charge Compression Ignition (HCCI) was perhaps the most attractive topic during
the last decade for engine combustion researchers so was subsequently investigated more intensively than other
engine technologies. Its application has stagnated at the present but its derivatives such as partially premixed
compression ignition (PPCI) still remain as promising alternatives to the conventional combustion systems. This
paper presents an overview of the research on HCCI and its derivatives and it also provides a future outlook of
the next generation of new combustion systems in relation to the concept of premixed compression ignition. It is
believed that multiple injections of multiple fuels using even higher compression ratios combined with boosting
will be the way forwards for high efficiency engines and this development trend will likely lead to merging of
diesel and gasoline engine technologies using premixed compression ignition.

Key words: gasoline engine, diesel engine, dieseline, homogeneous charge compression ignition (HCCI), partially premixed compression ignition (PPCI)