Here's an engine I designed and built with the following specifications: four cylinder, four cycle, gasoline engine, barrel engine, cylinders parallel to the shaft, with three moving parts. A major cause of air pollution is the burning of dirty fuels, diesel, and jet fuel. These can be eliminated using the cleaner fuel and gasoline that my engine uses. My engine would be suitable for trucks and other ground vehicles; aircraft propulsion could also be by ducted fan or gas/electric. A study after 9/11 showed that when all jet craft were banned for three days, there was a definite temperature change. I have a good working prototype of my engine running on gasoline. The main problem I see with current transportation is not the engine per se, but the use of dirty fuels. I think we can eventually eliminate turboshaft fuels that use dirtier fuels like diesel and jet fuel. Check out my prototype in the above video and contact email@example.com if you're interested in more data about the motor.