Strong synergies between ultralight mass, ultralow drag, and hybrid-electric drive can produce attractive designs for superefficient cars (and many other vehicles). A realistic near-term 4–5-passenger “hypercar” can achieve average fuel economy with much room for improvement. Depending on design details, mature ultralight-hybrid hypercars could achieve 60–120 km/l using virtually any fluid fuel, perhaps ultimately ~250 with fuel cells, while being safer, sportier, more comfortable and durable, cleaner, and probably cheaper than today’s cars. By using recursive design to maximize mass decompounding, optimizing for manufacturing cost can save far more fuel than traditional optimization for fuel savings. The dozens of technologies required are all demonstrated, but capturing their synergies with radical simplification requires highly integrated whole-system engineering with meticulous attention to detail. Despite the difficulty of this design challenge, market-driven commercialization is proceeding rapidly, with ~$1 billion committed and early entries possible in the late 1990s. The barriers are far more cultural than technical or economic. Implications for a wide range of industries—notably cars, oil, steel, and electricity—could be profound.