Based on what I have learned about this engine, there is very little contact internally since most of the moving parts are suspended by the air that is compressed within. I would think there are sealed bearings on the shaft, but there must be some kind of oiling.
This air engine is a realistic alternative that will probably surpass all other technology in the near future. These cars can run up to about 2 hours on a full tank of air. However, the idea is to put a gasoline engine that holds 1-2 gallons of gas that will run a motor to compress air once the air tanks start running low. They are stating that this could allow a car to travel close to 3000 miles on a few gallons of gas. AMAZING! This is well beyond what any hybrid or hydrogen fuel cell car, with virtually no polution at all.
This would use electricity, and in Europe where they get a lot more of their electricity from nuclear power, this would make more sense. Here, where most electricity comes from fossil fuel, it only changes where the emissions are, not whether there are emissions or not.
In addition, I would be interested in see how much energy this car takes to run versus an internal combustion car of similar size and performance.
How about an electric car with solar panels on the top and sides to keep the battery charged? You can charge it at night and then keep it charged with the panels during the day. Cars just sit around soaking up the sun during the day, can't they be charging up batteries? lazy cars.
I visited their web site. The engine can be used to compress air back to the tanks, a self re-fueling engine. That's way cool. But it takes longer to do that than stop at a fueling station.
It's still a neat idea.