The 4-stroke engine produces lower emissions than a 2-stroke for a number of reasons. They don't burn oil, and they have far better control of the air and fuel flow than a 2-stroke. The new direct injected 2-strokes, however, have reduced this gap by providing precise control of fuel and oil consumption, reducing emissions by up to 80% over conventional 2-strokes. Fuel consumption can also be reduced by up to 33% combined with a 50% reduction in oil consumption, all while retaining the power of a 2-stroke that boaters are expecting.