Internal combustion engines are now powering the vast majority of automobiles, motorcycles, trucks, boats and are also used in various industrial applications. They are so widespread because they can provide high power to weight ratios together with excellent fuel energy-density.

However, their efficiency is relatively low, despite all the technological advances. Most gasoline-powered engines, even when equipped with powerful turbochargers and electronic control mechanisms, can't produce a mechanical efficiency higher than 20%.

The most efficient one in the world is still in the prototype stage, but it promises to revolutionize the industry. The NEVIS (New Exhaust Valve & Intake System) engine is presented by the makers as having nearly doubled the fuel efficiency attained by conventional internal combustion engine technologies.

It operates using the Bortone Cycle, a new combustion cycle developed by the engine's inventor, Cesare Bortone and has been produced by The NEVIS Engine Company Ltd. While built using only currently used materials and methods, it features weight and size reduction due to the new piston, shaped like a doughnut and an important power increase compared to similar cylinder displacements.

This was possible by designing a new exhaust vacuum and a 6-fold increase in the number of power strokes per revolution. A prototype is now undergoing extensive testing in order to transform the project into commercially available applications in just a few years.

Another surprising feature of this prototype is its ability to run not only on gasoline, but also on diesel, hydrogen and biofuels, without important modifications.

It this will really prove to be as reliable, versatile and efficient as the manufacturers describe it to be, surely many people will be looking forward to a car that does 2 liters/100km (117 mpg). I would definitely buy something like this, even if it would fit into a car a little more beautiful than a cardboard box.