This invention is a projector headlight that, while offering dual beam patterns, boasts a 100% utilization of the light emitted from a light source by one of the following methods: (1) employing a reflective cutoff shield means to reflect the incoming light from said light source back to the reflector to enhance the illumination in low-beam pattern, (2) using reversible cutoff shield means to reflect the incoming light from said light source back to the reflector to enhance the illumination in low-beam pattern with no moving part involved, (3) utilizing a selective light-filter cutoff means to selectively reflect the incoming light from said light source back to the reflector to enhance the illumination in low-beam pattern without making use of any moving part, (4) using a low-beam light-emitting subassembly and a high-beam light-emitting subassembly that are separated by partition means to achieve dual beam patterns with no moving part, or (5) adopting a low-beam light-emitting subassembly in low-beam pattern and a high-beam light-emitting subassembly in high-beam pattern without any moving part.