Three decades ago, Volkswagen engineer Peter Hofbauer found himself staring at a Beetle engine’s cylinder head—that awkward slab of metal sitting on the combustion chamber—and wondering, Can’t we just replace that thing with more pistons? The answer turned out to be yes, so he eventually started a company, EcoMotors, to do just that. The company’s product is the opposed-piston, opposed-cylinder engine: OPOC. Each OPOC engine consists of two horizontal cylinders, each contain- ing two opposite-facing pistons. Twice the pistons per cylinder equals almost twice the power. OPOC weighs 30 percent less than the most efficient turbodiesel engines, and it has the highest thermal efficiency of any automotive engine in the world, converting as much as 50 percent of the energy in gasoline or diesel fuel into propulsion. A small OPOC-powered car could approach 100 mpg.
In 2010, Bill Gates and venture capitalist Vinod Khosla invested $23 million in EcoMotors, and this year the company signed development deals with a Chinese automotive supplier and the commercial truck manufacturer Navistar. Next it will demo a 1.2-liter, 160-horsepower OPOC in a compact sedan. Hofbauer says the engine is five to seven years away from commercialization, which would put it on the market well before federal fuel-economy standards rise to 54.5 mpg.