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Reducing engine swept volume (so-called ‘downsizing’) offers the potential to meet future tighter CAFÉ standards and reduced CO2 vehicle emissions in Europe. In downsizing the gasoline engine, a key challenge is controlling octane requirement without sacrificing fuel economy. The authors have investigated five alternative approaches on a turbocharged DI gasoline engine: Conventional stoichiometric operation, with reduced compression ratio (CR) Lean Boost DI (LBDI) with lean operation at full-load to control octane requirement while maintaining a high CR EGR Boost with cooled EGR dilution rather than excess air to control octane requirement Miller cycle concept, where valve-timing strategies are employed to reduce the effective compression ratio at high load Dual injection strategies to control octane requirement Each approach has been investigated using engine performance and vehicle simulation codes.