Orbital Engine company has many 2S air assised direct injection system in production vehicles today. Customers include Mercury Marine, Bombardier, Tohatsu, Aprilia and many others.
In the past few years OE has been working with 10 major automotive companies and has several concept engines being shown at auto shows now. OE has presented papers at SAE and other venues all over the world and is very active in design and testing of both 2S and 4S engines. Their engines meet or exceed emissions regs. thruout the world and typical fuel economy savings are 50% for 2S engines and 20% for 4S engines.
A group of us(has also formed a club(137) at:http://clubs.yahoo.com/clubs/oec
Check out Orbital Engines wesite at:http://www.orbeng.com.au/orbital/whatsNew/whatsNew.htm
If there is interest here please feel free to ask questions.