This supercharged and turbocharged spark-ignition engine combines a methanol reforming system with the direct injection of methanol fuel to extend the efficiency of internal combustion engines to more than 40% over conventional gas engines, and to more than 10% over clean diesel and typical gasoline/electric hybrid vehicles. This methanol-fueled engine system uses direct injection during high-load operation and, during low-load operation, sends a fraction of the fuel to an in-engine methanol reformer to generate a hydrogen-rich gas that improves combustion stability by speeding up the combustion process. Such increased efficiency at both load-ends of engine operation can enable engine downsizing. Reforming the methanol also reduces vehicle emissions to very low levels with lean or heavy exhaust gas recirculation (EGR) operation at low loads. This methanol-reforming/direct-injection engine could be employed with other fuels in addition to or instead of methanol, including gasoline, ethanol and natural gas.