General Motors revealed two drivable concept cars with new engines that burn gasoline in virtually the same way that a diesel engine burns diesel fuel.
The engines will get 15-percent better fuel economy than ordinary gasoline engines, GM estimates, but will not need the expensive exhaust treatment that diesel engines require.
Several car companies have been working on this type of engine technology, commonly known as homogeneous charge compression ignition, or HCCI. The technology promises the fuel economy of a diesel engine, which is typically much more efficient than a gasoline engine, but with the much cleaner exhaust of a gasoline engine.
It only works on a warm engine under light load right now but this looks promising to cut cruise fuel consumption for smaller engines that cannot use variable displacement. If they can extend the operating parameters farther out this could give hybrid-like boosts to fuel economy without the weight and cost of batteries.