You may have heard your car has a four-stroke engine, but you're not sure what that means. Why are there four? And what is a stroke, anyway? A modern gas engine most commonly uses pistons and a ...

Diesel engines, for all their rugged usefulness, can be tremendously polluting. They produce more NOx — nitrogen oxides-based emissions – than gasoline-fed cars, as well as more particulates, aka soot ...

Almost all gasoline engines, whether they're efficient-yet-less-refined four-cylinders, high-horsepower V6s, or growly and torque-rich V8s, use much the same process to create power. The "Otto cycle" ...